"The UAE has been a significant U.S. partner in Gulf security for more than two decades, and the alliance has deepened further in recent years in order to address multiple regional threats. The two countries sometimes have differed on regional priorities and the optimal means to utilize to counter the perceived threats. The UAE has a long-standing territorial dispute with Iran and has implemented economic sanctions against it, even though doing so has adversely affected some of the UAE's large and politically influential trading community. Suggesting continued wariness of Iranian ambitions in the Gulf, the UAE has sought--and received--U.S. assurances that the United States will maintain its commitment to Gulf security despite the United States'agreeing to a comprehensive nuclear deal with Iran. Under a 1994 U.S.-UAE defense cooperation agreement (DCA), about 5,000 U.S. military personnel are stationed at UAE military facilities, particularly the large Al Dhafra air base. The UAE was the first Gulf state to order the most sophisticated missile defense system sold by the United States (the THAAD), demonstrating support for U.S. efforts to assemble a coordinated regional missile defense network against Iran."
CRS Report for Congress, RS21852
Federation of American Scientists: http://www.fas.org/sgp/crs/index.html