A new study in the journal International Studies Perspectives examines U.S. foreign policy towards three Middle Eastern states and finds that the executive branch is often the driving force in foreign policy. Also, U.S. foreign policies tend to be reciprocal in nature.
Rachel Bzostek, Ph.D., and Samuel B. Robison, M.A. conducted a quantitative and qualitative analysis of the influences on U.S. foreign policy toward Israel, Iraq, and Saudi Arabia from 1981 to 2004.
Results show that the executive branch is the primary force driving policy towards those Middle Eastern states. Congress may seek to influence or mold policy and oftentimes does in significant ways. However, its ability to truly direct policy is limited.
Also, the policies engaged in by the U.S. tend to be reciprocal in nature. More often than not, the United States tends to "reward" states that adopt policies the U.S. likes and "punish" states that engage in behaviors disapproved of by the U.S.
Explore further: Ig Nobel winner: Using pork to stop nosebleeds