"Human rights conditions in China and the threat of proliferation of weapons of mass destruction resulting from China's lack of export controls or lack of cooperation with international export control standards continue to be the main foreign policy or national security issues that hold these economic restrictions in place. The influence of Congress on U.S. policy toward China, once significant because so much hung on the annual possibility that favorable trade terms could be suspended, has more recently been diffused. Sanctions that remain in place today can all be modified, eased, or lifted altogether by the President, without congressional input (though some changes would require that the President notify Congress). Congress and the Administration each recognize the importance of China's emerging ability to consume and to produce, and China has become an increasingly important trading partner of the United States. Several recent national security developments -- North Korea's pursuit of nuclear weapons and crises brought before the United Nations Security Council -- have strained U.S.-China political relations. China, as North Korea's benefactor and primary trading partner, is the power most likely to keep that country at the bargaining table over its nuclear intentions. In the U.N. [United Nation] Security Council, both the United States and China, as permanent members, have the ability to block any proposed action. China has emerged as a contrarian when economic sanctions might be considered in the Security Council."
CRS Report for Congress, RL31910