国际体系正在迅速变化之中。没有任何人完全理解其变化。许多人批评奥巴马政府没能澄清美国在未来世界中能够扮演何种角色。奥巴马政府固然做不到,其他历史学家、分析家和政治家同样也做不到。包括政府的最强有力的批判者在内,大家都做不到。决策者在试图去澄清美国未来角色之时,心里至少应当清楚 The international system is rapidly changing. No one understands its change completely. Many people criticize the Obama administration for failing to clarify what role the United States can play in the future world. Although the Obama administration can not do it, other historians, analysts and politicians can not do the same. Including the most powerful critics of the government, we can not do it. At the very least, policymakers should at least be aware of when trying to clarify the future role of the United States