“Freedom of navigation” is an important principle of maritime international law. Since the UN Convention on the Law of the Sea （UNCLOS） came into effect， the principle of free navigation has been established in international law through legislation. However， because the Convention does not regulate navigation activities in all aspects and it is vague in parts， disputes have continuously appeared as new situations develop. In recent years， China’s efforts to safeguard its maritime rights have been attacked by some Western countries， such as the US， who claim they impede the freedom of navigation. As China is “going global，” it also needs the freedom of navigation to be protected. It is necessary to take a new look at the international legal framework for navigation freedom and China’s policy choice.
　　Characteristics of Contemporary Navigation Freedom System
　　Before the 1958 Convention on the High Seas， freedom of navigation was just an implicit part of the “freedom of the high seas.” The Convention on the High Seas clearly stipulated for the first time the legal principle of “freedom of the high seas” and its four aspects， of which freedom of navigation took priority.
　　Due to the extensive use of the Convention and the acceptance of most of it by those countries that are not signatories， such as the United States， it could be said that the principle of freedom of navigation is now widely accepted as one of the basic principles of international maritime law. The Convention not only sets rules for issues concerning navigation on the high seas， but also stipulates the rights and obligations of various sea areas which have different legal statuses with regard to freedom of navigation. As a result， freedom of navigation has changed from a principle accepted in practice to one where legal stipulations are established via the Convention. The Convention covers passage and transit through various waters， including territorial waters， adjacent areas， straits used for international navigation， archipelagic waters， exclusive economic zones as well as use of the high seas， and there are legal stipulations covering various freedom of navigation issues such as the rights of non-military vessels， sea lanes， the jurisdiction of flag nations and the jurisdiction of coastal states.
　　The Convention being taken as the core， the international statute laws as the major legal basis and the international common law as the supplement
　　Although the Convention stipulates the rights and obligations of various parties in different sea areas and other issues of maritime navigation in a comprehensive way， it is not the only international law that administrates maritime navigation. Other international conventions also regulate the rights and obligations of navigation in an effective way. In fact， there are more and more legal restrictions on maritime navigation. Even navigation on the high seas is facing more stipulations and restrictions under different international laws. Taking an overall perspective， the Convention is used as the core legal basis while other international conventions related to maritime navigation elaborate such provisions as navigation rights and obligations accordingly. Thus freedom of navigation has already been included in international law. Besides the UN Convention on the Law of the Sea， which comprehensively regulates navigation in different waters， there are other international conventions that set stipulations and restrictions on different aspects of maritime navigation， including the 1969 International Convention Relating to Intervention on the High Seas in Cases of Oil Pollution Casualties， the 1972 Convention on the International Regulations for Preventing Collisions at Sea， issued by the International Maritime Organization （IMO）， the 1973 International Convention for the Prevention of Pollution from Ships （MARPOL） and the 1988 Convention for the Suppression of Unlawful Acts against the Safety of Maritime Navigation. These are also parts of the legal system covering freedom of navigation. 　　But it is also true that the rules concerning freedom of navigation have not all become statute despite the enactment of the UN Convention on the Law of the Sea and other conventions. For example， the stipulations covering the activities of military vessels or government public service vessels are relatively vague. This is because there is a multiparty game of interests during the negotiations for such international laws. In addition， international agreements are only legally binding for the contracting parties and this has given room for international common law to exist. Nevertheless， the development of international common law is slow. Its content needs repeated acceptance by the international community before being confirmed. At the same time， changing its content is also very hard. A common conduct will remain valid unless international legislation clearly changes it. When trying a case， the international court of justice will seek to balance between international agreements and international common conduct. They will quote the common conduct to explain the meaning of the international law and make clear the boundaries of the force of international agreements.
　　There is no complete definition in any international convention on what navigation is and what types of ships should be regarded as the subject of such navigation. This is a matter of international common law. From the perspective of practice， legitimate use of international laws related to freedom of navigation includes maritime activities that are not banned in the statutes and the subjects of free navigation does not exclude military vessels or public service vessels of governments. Thus after the Convention came into effect， international common law still plays a supplementary role in the freedom of navigation system.
　　From focusing on “freedom” to stipulating the rights and obligation of “navigation”
　　In the period when freedom of navigation only existed as a concept， the freedom of navigation concentrated on the “freedom” instead of how to navigate. This is a defect of the 1958 Convention on the High Seas， which set the development direction for international legislation afterwards. But the UN Convention on the Law of the Sea not only reaffirms the principle of freedom of navigation， it also stipulates the rights and obligations of ships and coastal countries in and through different sea areas on the issue of navigation. For instance， the Convention entitles the right of innocent passage to ships of other countries passing through the territorial seas of a country while listing twelve activities such ships cannot do. It also stipulates a coastal state can enact laws and regulations covering nine issues relating to the innocent passage of foreign ships， and stipulates that a coastal state has the obligation not to hinder the innocent passage of foreign ships. The Convention adopts the same legislation mode about navigation issues in straits， archipelagic waters and exclusive economic zones， etc. Even with regard to the high seas， which enjoy the greatest freedom of navigation， the Convention adopts the method of correspondence legislation and stipulates the rights and obligations of navigation. For example， while stipulating that ships are under the jurisdiction of the laws of their flag nations， it also requires a real connection between the ships and the flag nations. In addition， the Convention requires countries to strictly manage the ships under their flags to ensure maritime security. It also requires the flag nations to jointly shoulder the obligation to combat pirates and crimes on the sea. 　　To talk about freedom in an abstract way is only emphasizing “rights.” But rights come with obligations. There cannot be concrete rights without explicit obligations. More and more international conventions are making clear the navigation obligations in different sea areas which seem to be restrictions on freedom of navigation， but which are actually defining the boundaries and connotations of freedom of navigation. From a general view， according to the Convention’s distinction of different sea areas， the number and scope of the rights of free navigation decrease from the high seas to territorial waters， while the obligations correspondingly increase. From the view of the historical trend， the number of legislations that restrict navigation freedom is rising. But the legal protection of the rights to freedom of navigation is increasing. Examples include requiring a coastal state to give due publicity to all such laws and regulations； asking a coastal state to give appropriate publicity to any danger to navigation of which it has knowledge within its territorial waters； and requiring a coastal state to take appropriate measures to ensure the safety of navigation by establishing reasonable safety zones around artificial islands， installations and structures it is building in its exclusive economic zone.
　　From emphasizing non-interference in navigation to coordinating the stipulations on the right of navigation and other elements
　　The Convention on the High Seas and the international common law prior to it mainly emphasized that freedom of navigation should not be interfered with or hindered by the coastal states or other countries. After that， many new trends and elements influenced navigation and caused conflicts， which can be mainly seen in the conflicts between the right to navigation and the right to economic development， between the right to navigation and protecting the marine environment， and between the right to navigation and the security interests of the coastal states. The UN Convention on the Law of the Sea coordinated and regulated these different rights.
　　For example， in order to safeguard the safety of maritime navigation， it was necessary to set up international laws to avoid vessels colliding. In addition， freedom of navigation should not involve illegal activities or crimes recognized by the international society， such as piracy， maritime terrorist activities and so on. Moreover， in exclusive economic zones， the construction of artificial islands or the demarcation of fishing zones by the coastal states could contradict with navigation safety， which called for a balance between the safe navigation of ships and the commercial use and exploitation of the sea by the coastal states. One more example was the potential leaking of fuel and crude oil caused by navigation accidents that would cause damage to the marine environment. Thus higher requirements were made for safe navigation. The subjects of navigation no longer include all types of ships. Although military vessels and governments’ public service vessels still enjoy jurisdiction exemption， the Convention has listed out the obligations of navigating warships， other military vessels and governments’ public service vessels in many of its provisions. For instance， when a warship is innocently passing through the territorial sea of another country， it should not pose any threat or use force against the sovereignty， territorial integrity or political independence of the coastal state， should not conduct military exercises or practice with weapons of any kind， and should not collect information to the prejudice of the defense or security of the coastal State. Another example is the stipulation that in territorial waters， submarines and other underwater vehicles are required to navigate on the surface and to show their flag. With the development of military technology， foreign military vessels could show force in the exclusive economic zone of a country， which poses threat to the sovereignty security of the coastal state. Therefore， there are disputes between maritime powers and coastal states about whether military vessels enjoy full freedom of navigation and other activities in exclusive economic zones. There is little in the Convention on this issue， and thus it is becoming one of the hotspots for the improvements needed in the international legal system covering navigation freedom. 　　From a game of interests between nations to the coexistence of both the game and co-governance
　　Though the game of interests between nations is still the major factor influencing the international legislation covering navigation freedom， the international community has started to cooperate on such law-making in face of the environmental problems confronting all humans， so as to seek a balance between navigation freedom and environmental protection. The protection of the marine environment has become an important element in making the rules and regulations for navigation which has been raised to the height of the interests of the whole mankind by the Convention and has quickly become a basic principle of international maritime law. Provisions on environmental protection have been written for various water types of different legal status. Even for the high seas which do not belong to any country， environmental protection is stipulated in international law. These laws and regulations impose certain restrictions on navigation. Compared with the issue of climate change where there is a fierce game of interests between nations over their emissions reduction obligations， the issue of marine environmental protection has seen more cooperation and co-governance among nations.
　　Since no country can completely control and occupy the sea， the range and boundaries of navigation freedom are mainly demonstrated by the interest game between maritime powers and coastal states. The high seas are generally in a “free” unregulated state. But with the establishment of the exclusive economic zone system， the range of proper higher seas has been narrowed to a large extent. Meanwhile， global climate change and marine environmental disasters require coordinated activities by countries. International terrorism and other criminal activities require even more cooperation of the international society on the regulation and management of maritime navigation. The concept of “co-governance of the sea” has become the new driving force for the development of the international legislation covering maritime navigation.
　　Many international non-governmental organizations have played a positive role in pushing forward international maritime legislation. Through their appeals and activities， these organizations without boundaries have changed the calls and the voice of the public to the determination of co-governance by the international community. NGOs such as Greenpeace， the Worldwide Wild Fund （WWF） and Sea Shepherd are playing significant roles in this respect. The efforts of NGOs can be seen in many areas including restricting the dumping of waste into the sea， regulating nuclear powered vessels， and raising the standards of shipbuilding and navigation with the aim of reducing carbon emissions. These NGOs often call for nations to cooperate in international legislation and strive to alleviate the intensity of the conflicts in interests between them. 　　Existing Problems and Legal Disputes
　　Although the maritime navigation legal system represented by the Convention has been established， it is still in a preliminary stage， and there are still imperfections in terms of freedom of navigation. In particular， the Convention is still vague with regard the conflict between the right of navigation and other interests， which can be seen from the following aspects.
　　Use and exploitation of resources in the exclusive economic zone and navigation freedom
　　According to the Convention， coastal states have the sovereign right to explore and exploit the natural resources in their exclusive economic zones. However， when the coastal states produce wind energy， exploit oil in the seabed or set up facilities for certain fish farming areas in their exclusive economic zones， the equipment and facilities could have negative impacts on the use of existing sea lanes and safe navigation. For instance， when the part of a fish farm overlaps with the sea lane， what measures should be taken to avoid navigation accidents？ Or when an oil exploiting area overlaps with the sea lane and a fish farm， how should people demarcate the boundaries between them？
　　The Convention requires that when the coastal states are exercising their rights， they ought to “have due regard to the rights and duties of other states and shall act in a manner compatible with the provisions of this Convention.” Nevertheless， it is just a provision of principle. The Convention does not stipulate concretely the conducts and procedures of “due regard to the rights and duties of other states.” For example， how should a coastal state notify the international community of a fish farm near a sea lane in advance？ The coastal states do not need to get the approval of foreign countries before they explore and exploit the natural resources in their exclusive economic zone. Nor do they need to inform or register with any international maritime organization. There is the possibility of conflicts between the right to exploration and exploitation of the coastal states and the right of vessels to free navigation.
　　Military activities in exclusive economic zones and navigation freedom
　　There is also a huge divergence on military activities in exclusive economic zones. On the one hand， the maritime powers believe that the navigation freedom of military vessels is part of the freedom of navigation. Traditional international common law has not set restrictions on the content and range of the activities military vessels can engage in on the high seas. Moreover， the Convention extends “navigation freedom on the high seas” to exclusive economic zones， and there is no provision restricting the related activities. Hence it is legal for foreign military vessels to navigate， carry out military exercises， gather intelligence and conduct military surveillance and so on in the exclusive economic zone of another country. On the other hand， based on Article 88 of the Convention and out of consideration for the national sovereignty and security of the coastal states， the activities of foreign military vessels in the exclusive economic zone should not go against the goal of peace. And activities such as military exercises， intelligence gathering and surveillance have nothing to do with peaceful use of the sea and thus should be approved by the coastal state in advance. 　　Such divergences and disputes reflect the political reality of the current international community. Having advanced military technology， a maritime power could when outside its own territorial waters， pose a threat to a country’s independence and security. For example， military technologies such as reconnaissance satellites， intermediate and long range missiles and long-range artillery have disabled the traditional shield of a territorial sea which safeguards national security. Under such a circumstance， it is necessary for the coastal states to consider their national security interests outside the 12 nautical miles of their territorial sea. The stipulation of the Convention which extends free navigation on the high seas to the exclusive economic zone cannot solve the contradictions and conflicts in reality. For instance in 2014， under the name of freedom of navigation the United States challenged 18 countries and regions including China， India and Ecuador by conducting military measurement and reconnaissance activities in their territorial waters. Countries such as China and India have protested against such behavior.
　　In fact， while the Convention admits the legitimate interests of the coastal states， it also admits the right of other countries to free navigation. There is no explicit balance between the two and thus different parties often explain the Convention in a way which is beneficial to themselves. However， this may be the reason why the Convention is a huge success – it has taken into account the concerns of different countries and has confirmed their rights through international law. But such a method has left some vagueness， leading to conflicts between the national defense security interests of the coastal states and the navigation interests of other countries.
　　Environmental protection and navigation freedom
　　Likely， based on their right to exploit the resources in their exclusive economic zones， coastal states will try to limit the sea lanes， require compulsory pilotage， ask for higher safety technology standards for navigating ships and higher emission standards， etc. for the purpose of protecting the marine ecology and environment. For instance， Australia has made a lot of efforts to protect the Great Barrier Reef. Yet although there is no subjective discrimination， exorbitant vessel technology standards could restrict the passage of ships belonging to developing countries. This could bring about worries about freedom of navigation and thus has attracted the attention of the International Maritime Organization. The conflict between navigation freedom and marine environmental protection has become an increasingly significant matter of concern to the international community. 　　When there is a shipwreck， a ship can sail to a nearby sea for help. This is regarded as a legal right in the international common law. However， with the purpose of protecting the ecological environment， the relevant country may refuse a damaged vessel which might pollute the marine environment due to fuel or crude oil leaks to enter its ports， gulf or exclusive economic zone. So there is a conflict between the right to seek refuge and environmental protection. For example， in 1999 and in 2002 respectively， two tankers in distress， the Erika and the Prestige， were refused entry to near shore waters for refuge and both finally sank. Such incidents pushed the International Association of Independent Tanker Owners （INTERTANKO） and the Baltic and International Maritime Council （BIMCO） to call for an international agreement clearly stipulating that shipwrecked vessels should be provided with safe refuge. Nevertheless， the coastal states will not sacrifice the environment of their coastal waters or ports by letting damaged tankers into their administration area unless lives are threatened.
　　With suspicions about the safety of nuclear-powered vessels， some countries refuse the entry of this type of vessel into their commercial ports， or restrict them to using specific parts of sea lanes. Based on navigation freedom， the owner nations of these ships ask for the right of innocent passage through the territorial seas of the coastal states. According to Article 22 and 23 of the Convention， coastal states can require tankers， nuclear-powered ships and ships carrying crude oil and nuclear materials to use such sea lanes and traffic separation schemes as they may designate or prescribe when passing through territorial sea areas. But the Convention has not entitled the coastal states the right to refuse or forbid the vessels of these types to pass through their exclusive economic zones. The Convention only requires the coastal state to “have due regard to the rights and duties of other states and shall act in a manner compatible with the provisions of this Convention” when exercising their right of jurisdiction. This has given rise to conflicts between the marine ecological and environment protection of coastal states and the navigation interests of other countries.
　　Collective security and navigation freedom
　　Based on international common law， when a ship is navigating outside any territorial waters， it is only subject to the jurisdiction of the law of the flag nation. It has no obligation to report its location， information about its crew and cargo to any country except the flag nation. However， quite a few countries pursue an open policy of ship registration. Consequently， flags of convenience cover many illegitimate activities at sea. Under the excuse that vessels are only subject to the jurisdiction of the flag nation， the smuggling of drugs， arms and illegal immigrants and other crimes at sea cannot be effectively controlled. 　　The impact of crimes and terrorism at sea is no longer limited to only several regions or countries. For example， Somali pirates have aroused the concern of the international community. Many countries have dispatched military vessels to conduct peace-keeping activities in this region. But as of now these countries are mainly protecting commercial ships of their own as there is no collective mechanism in place. The Convention does not give a nation the right to enter another nation’s territorial seas even to fight against crimes. The activities targeting the Somali pirates are based on the resolution of the UN Security Council and the publicly declared approval of the Somali government. Piracy is also rampant in the Strait of Malacca. Yet even though the capacities of nearby countries to combat pirates are limited， they have refused the involvement of the international community under the name of protecting their national sovereignty and security. In this region， navigation freedom is in contradiction with protecting national sovereignty.
　　To serve the goal of anti-terrorism， the United States has not only strengthened the monitoring of ships navigating near its coast， but also requires ships which are outside its 12 nautical miles of territorial sea but sailing towards the US ports to provide information about their location.
　　Besides， the United States has reinforced its cooperation with the IMO and has tried to promote the ship-borne Long-range Identification and Tracking （LRIT） system. Australia has done even more. In 2005， the country launched the Australian Maritime Identification System （AMIS）， requiring vessels that are sailing toward Australian ports to provide information including a vessel’s registration， crew members， cargo and berthing port（s） on their own when such vessels are 1，000 sea miles or 48 hours from the Australian coast. What is more， vessels passing though the economic exclusive zone or the territorial sea of Australia are asked to provide relevant information for possible examination when they are 500 nautical miles or 24 hours of navigation away from the coastline of Australia. Such requirements are far beyond the stipulations of the Convention. Thus “Freedom on the high seas” is being eroded by domestic laws issued for “anti-terrorism” and “national security.”
　　Some countries are worried that this could influence the navigation freedom of other countries or even become the excuse for major powers to interfere with or hinder the maritime trade of certain countries. They have many doubts. Does the IMO have the right to make mandatory regulations requiring all the commercial ships to be equipped with identifying technology？ Will this harm the security interests of the flag nation？ When a vessel is not willing to cooperate， does a nation have the right to board and examine a vessel in its exclusive economic zone or on the high seas？ How can the guarantee of collective security not to be used by maritime powers as a tool to hinder the navigation freedom of other countries？ There are no provisions in the Convention answering these questions. Thus it can be seen that there exists a conflict between the security of a nation and that of other nations as well as a conflict between the security interests of a nation and the interests of free navigation of other nations. 　　The right of jurisdiction of the coastal states and navigation freedom in the Arctic region
　　As a result of global warming the Arctic area near the territorial sea of Russia and Canada is becoming a “northern sea lane” which has practical navigation values. Navigation via the Arctic sea lane between Asia and Europe or between Asia and North America shortens the journey by several thousand sea miles， saving time and fuel. However， because of geographic conditions， the feasible sea lanes in this area are usually very close to the territories of the countries near the Arctic. In some parts， these sea lanes even need to go through territorial seas. Under such a circumstance， coastal states may impose unreasonable restrictions on commercial navigation. Or they could forbid the passage of foreign ships under the name of protecting their national security interests. In addition， foreign tankers and nuclear-powered commercial ships arouse the worries of the coastal states about protecting their marine ecology and environment. The coastal states may refuse passage or set high-standard navigation restrictions based on their pragmatic interests. They may even require compulsory pilotage.
　　To protect navigation freedom in the Arctic sea lanes is also significant to the commercial interests and national security interest of countries not on the periphery of the Arctic. From the view of the special navigating conditions of the Arctic， nearby countries certainly have more jurisdiction compared with common coastal states as well as stronger control – probably it is very hard to directly apply the rules of the Convention to the Arctic region. Maybe navigation in the Arctic region needs special rules to seek a new balance between the interests of coastal states and that of navigating countries. In fact， the IMO is speeding up make a “Code of Safety for Ships Operating in Polar Waters.”
　　China’s Policy Choice
　　In the past， China had very limited power to protect its maritime sovereignty. Besides， its center of economic development was on land. Therefore， China’s participation in the construction of international maritime laws focused on the guarantee of its interests in its exclusive economic zone and territorial sea. Given such a background， China’s maritime laws are mainly focused on its territorial sea and the exclusive economic zone. Meanwhile， the focus of its academic research is on the prevention of foreign intervention by seeking legal foundations in international maritime law to protect infringements on its national interests. But with its “going out，” China has continuously deepened its dependence on the sea. It is now in urgent need of practical guarantees for its ocean trade and energy transportation. Meanwhile， the offshore defense capabilities of China have greatly improved. From the view of development， China should exercise more foresight on the issue of navigation freedom. It should especially pay attention to protecting both its maritime interests and overseas interests. 　　Protecting territorial sovereignty and navigation freedom
　　In recent years， under the banner of “protecting freedom of navigation，” the United States has interfered with the sovereignty disputes over islands and reefs in the South China Sea between China and some countries such as the Philippines and Vietnam. Since the second half of 2015， the United States has dispatched naval vessels and air force planes several times and intruded into the offshore sea area or the airspace of the islands and reefs of China in the South China Sea， posing threats to the security of China’s islands and reefs as well as the safety of people on them. In fact， the “freedom of navigation” claimed by the United States is just intelligence gathering in China’s offshore sea and a military exercise which threatens the freedom of other countries by using military vessels and aircrafts. This has no connection with the navigation freedom in international law. Actually， the navigation freedom of non-military shipping is not restricted in the South China Sea， except for ships that are conducting illegal fishing or illegitimate exploitation of resources. As long as they comply with the relevant laws of China， the innocent passage of vessels has never been impeded. Currently， in terms of the “right of innocent passage” through territorial seas stipulated in the Convention， China and some other countries propose ships get the approval of the coastal states in advance. Therefore， on the issue of protecting territorial sovereignty and security interests， China firmly holds to its bottom line， opposing any behavior that seeks to infringe on China’s territorial sovereignty under the banner of “freedom of navigation.” But at the same time， China should realize in protecting its territorial sovereignty， it should also protect foreign vessels’ right to navigation freedom as prescribed by international law so as to avoid a negative impact on common navigation freedom caused by inappropriate expansion of jurisdiction over the sea.
　　Reexamining the laws and rules on navigation in the exclusive economic zone
　　In their exclusive economic zones， coastal states enjoy sovereign rights to explore and use the natural resources and protect the environment. Hence China should strengthen its legislation in this respect， which would not only fully demonstrate its sovereignty but also create favorable legal conditions for economic development and environmental protection， facilitating full use of the exclusive economic zone. Meanwhile， the Convention has no concrete provisions restricting the sailing of military vessels in another country’s exclusive economic zone. Too much emphasis on the prohibition over foreign military vessels banning military measurement and intelligence gathering in China’s exclusive economic zone does not prevent such incidents from happening. Thus China should not oppose the activities of foreign military vessels in the exclusive economic zone in a general way， but should consider whether such activities harm its security. China should employ appropriate alarms or keep-out measures which are proportional to the hazardous level of the foreign military activities in order to protect its national security. 　　In essence， the protection of national sovereignty and security relies on being a strong maritime military power. Other countries may take into account the military strength of China and consequently reduce or give up observation and military measurement in China’s exclusive economic zone. The US activities of military reconnaissance and measurement in China’s South China Sea can be taken at as an example. With of its high altitude satellite reconnaissance， the United States carries out military reconnaissance activities in the South China Sea sometimes for military intelligence gathering， but sometimes to challenge China’s proposition that foreign vessels cannot carry out military reconnaissance and measurement in another country’s exclusive economic zone. Therefore China should have different responses. Provocation under the name of freedom of navigation is part of the US global strategy. It is not merely targeted at China. In the past， it was also often used to challenge India and the others who held similar stances to China. Nevertheless， in order to be in line with its “rebalancing to the Asia-Pacific” strategy， the US navy and air force have explicitly reinforced their military presence in the South China Sea.
　　When the provocative reconnaissance activities of foreign military vessels harm China’s national defense security， China’s military certainly has the right to take measures to stop them. This is permitted or at least not banned by the Convention or international common law. For instance， if US military vessels and aircraft carry out reconnaissance and intelligence gathering activities near China’s submarine base in the South China Sea， which harms China’s national security， it is in conformity with international law for China to take measures to stop the United States， for such activities endanger the country’s national security and interests and go against the aim of peaceful use of the sea. In the meantime， China should strengthen its studies on the legal issues concerning keep-out measures.
　　With China’s naval strength growing from the offshore sea to the far ocean， its military vessels need to increase their long-distance navigation activities. China’s navy has started to show up in straits used for international navigation， such as the Aleutian Islands， Hawaii and the Miyako Strait of Japan or in the exclusive economic zones of other countries. For safe navigation， China also needs to collect underwater information of the lanes for its military vessels. This does not pose a military threat to the coastal states and has never been opposed or protested by other countries. Besides， the activity of China’s navy protecting the commercial ships near Somalia also involves passage through a foreign territorial sea， exclusive economic zone and straits used for international navigation. It should be seen that the activities of foreign military vessels in the exclusive economic zone of a foreign country do not necessarily harm the national defense security of the coastal states. Whether it is a threat depends on many elements including the target， the purpose and the content of such military activity. 　　Attaching importance to studies on the guarantees in international law for the military activities at sea in peacetime
　　In order to carry out the strategy of maritime power， a country has to give up some of the traditional and conventional recognition of international law. Although the Convention says the use of the sea should be for peaceful purposes， it does not mean maritime military activities should be completely rejected. It can be argued that military activities also strengthen peace at sea， such as cracking down on piracy and terrorism and participating in preventing of the spread of the weapons of mass destruction. Hence China should enhance its legal studies on maritime military activities in peacetime. It should see the practice of foreign military activities at sea and determine guidance for itself.
　　For example， in response to the multinational “Proliferation Security Initiative” （PSI） aimed at stopping the trafficking of weapons of mass destruction， their delivery systems， and related materials， China should strengthen its efforts against proliferation within the system of the United Nations and firmly object to unilateral coercive measures which could violate the Convention. China should insist on the principle of cooperation and the collective activity of the international community， advocate the building of cooperation institutions within the system of the United Nations， push forward the realization of an intelligence sharing mechanism and the mandates for action mechanism， and oppose the inappropriate measures and activities which abuse the right of visit and examination， abuse the right to crack down on crimes and terrorism， or impede the freedom of navigation and trade.
　　Actively proposing free navigation in the Arctic region
　　China has no claim to sovereignty in the Arctic region， but the Arctic sea lanes are significant for China to safeguard the security of sea lanes in the future. On July 1st， 2015， the 12th Standing Committee of the National People’s Congress passed “The National Security Law of the People’s Republic of China，” raising “security at the poles” to the national level. Besides the security aspects， the Arctic region also has important significance as a sea route to China. After becoming a formal observer of the Arctic Council， China should take good advantage of this platform by advocating the position which is in line with its foreign policy and actively participate in the drawing up of laws and regulations for the Arctic sea lane. 　　Based on “the Convention，” China should deny excessive claims of jurisdiction over relevant sea areas by some countries which advocate freedom of navigation for this purpose. This issue involves how Arctic periphery countries demarcate the baseline of their territorial seas， how they determine from which part is the internal waters and whether the straits between relevant islands and the continent meet the requirement of the straits for international navigation， etc.
　　The different legal natures of various water areas define the scope of navigation freedom， therefore， these questions are highly related to the navigation interests of the international community.
　　Meanwhile， China should learn from the protection experience of the Antarctic region and the positive fruits of the “Antarctic Treaty” in the discussion of the Arctic region. Rules for military navigation passing through the Arctic region should be distinguished from those for the common high seas or exclusive economic zone in response to the worries of the countries in this region about their national security interests.
　　In addition， China should actively advocate for the freedom of navigation for commercial ships and not allowing the coastal states to overly control the Arctic sea lanes with the excuses of security and environmental protection. Excessively high standard of vessel construction technology and compulsory pilotage could form a technology barrier， impeding the navigation of commercial ships in the Arctic region.
　　Influence of the measures to handle climate change and marine environmental protection on the freedom of navigation
　　Under the circumstance that the whole world is concerned about climate change， the international society is starting to seek a way to reduce the carbon emissions from the vessels. However， some Western countries which have technological advantages in ship construction attempt to unilaterally limit the berthing of some passing ships in their ports with the excuse of reducing the pollution from vessels， which is an unreasonable restriction on the freedom of navigation. Some countries impose restrictions on the types of vessels that can enter their ports： only vessels that meet certain standards are permitted to enter and exit their ports. To China， this severely impedes the operation of its commercial ships and it constitutes technology and environmental protection barriers that damage free competition. To handle this issue， China should unite with other developing countries， jointly oppose domestic and regional legislation which unilaterally limits freedom of navigation， and propose proper emission standards that are established by relevant international organizations based on the principle of “common but differentiated responsibilities.” 　　At the same time， to protect living marine resources and biological diversity， there are calls for the demarcation of marine ecological protection zones. To certain extent， such calls are reasonable. But like the pollution restrictions on vessels mentioned before， inappropriate and unreasonable marine biological reserves and other unreasonable restrictions on vessel types or shipping conditions will have a negative impact on China’s commercial navigation. To find out how to limit the impact while actively taking part in the international environmental protection efforts， China needs more participation in the legislation activities of international organizations while opposing the unilateral measures of coastal states which impede and limit the freedom of navigation.
　　Conclusion
　　A legal framework for freedom of navigation has basically been formed. However， the problem of balancing navigation freedom with other interests has not been completely solved. Meanwhile， as the international community is becoming a “global village，” new problems are pushing different countries to express diverse values and interest propositions in the protection of freedom of navigation freedom. This interaction between the pursuit of values and interest propositions means the maritime navigation legal system is continuously changing and developing.
　　The subject， scope and content of the rights and obligations set out in the legal system for navigation freedom have seen great changes without being noticed by the public. As to the subject， the connotation of “freedom” is diverging between that for commercial ships and military vessels and vessels for public service. In terms of the scope， the geographic scope of navigation freedom is narrowing with the gradual completion of legal systems covering different sea areas. And speaking of the content， coastal states are seeing an increasingly larger right of jurisdiction over the seas around them； and the international society is seeing more and more joint regulation on the rights and obligations of navigation. The system governing navigation freedom is showing systematic characteristics. It is becoming a relevant independent field in maritime law. At the same time， balancing navigation freedom and national sovereignty and security， and the exploration and exploitation of marine resources and marine environmental protection will become the focus of maritime legislation in the future. It is both a mission and a trend of future international legislation to distinguish between commercial shipping and military activities and to make clear laws and rules for them.
　　With the progress of China’s economic development and strength， the focus of its national interest is no longer limited to the land and offshore sea areas. China should make some changes in its attitude toward the legal framework for navigation freedom. It should timely adapt to the changes in its overall interest pattern and comprehensively consider the nation’s territorial security， economic security and environmental security， and establish a legal position on navigation freedom which is in accordance with its integral national security thinking. Also， China should try to enrich the content of laws covering navigation freedom and make clear relevant obligations.