The objective of this work is to analyze the economic, political, and commercial relations between Singapore and U.S. using the defensive neorealism of Joseph Grieco (2000) to identify the rationalization of power of the strong actor and the voice opportunity to the weaker actor in a cooperative environment. This purpose considers two hypothesis, the first sees USSFTA as a great step toward winning stability in the southeast for American investors, open markets, tariff reduction, high protection of property rights and creation of a efficient dispute settlement system. Added to that, such agreement would permit the strategic use of cooperation that could ease the US engagement and its political influence in the Asian southeast, so the USSFTA would ease a respond to the common challenges as terrorism and the protectionism of others regions. The second hypothesis to be verified is related to the decision of Singapore to go beyond the precedent regional agreements and accept the USSFTA; in return, this City-State would acquire voice opportunity and accommodation with a great power to guarantee its regional security, FDI attraction and economic growth.