In 1985 , President Ronald Reagan requested the expansion of the program and Congress enacted the International Security and Development Cooperation Act , which expanded the statutes that supported the Federal Air Marshal Service . The FAM program was begun in response to domestic hijackings and FAM operational flights were almost exclusively conducted on domestic U.S. flights until 1985 . After the hijacking of TWA Flight 847 in 1985 and the enactment of the International Security and Development Cooperation Act , the number of FAMs was increased and their focus became international U.S. air carrier operations . Due to resistance of several countries including the United Kingdom and the Federal Republic of Germany to having individuals carrying firearms entering their countries , the coverage of international flights was initially limited . Resistance to the entrance of armed personnel to their countries was overcome through negotiations and agreements about the terms and handling of weapons when they were brought in country . Hence the FAMs could operate worldwide in carrying out their mission to protect U.S. aviation from hijackings
TWA Flight 847
TWA Flight 847
Federal Air Marshal Service