Over the years, the international regime had struggled to constrain the spread of nuclear weapons. However, there were some states still pursuing nuclear weapons or secretly possessing it. Iran and Israel were the prominent examples. United States put double standard in response toward these countries nuclear program. U.S. put efforts to prevent and punish Iran while support Israel for developing nuclear weapons. By using the theoretical framework from William D. Coplin about Decision Making Process, this undergraduate thesis analyzed about the reasons behind U.S. foreign policy toward Israel in supporting its nuclear weapons program. It included the factors that influence U.S. decision makers from international context, domestic politics, and economic & military capability. The method of this research followed the deductive and qualitative method. The writer collected data from an extensive research toward relevant sources both in printed and online sources such as books, academic journals, report, newspaper and websites.