In 1973, Libya claimed much of the Gulf of Sidra (south of Latitude 31° 30′) as its territorial waters and subsequently declared a "line of death", the crossing of which would invite a military response. The United States did not recognize Libya's territorial claims and continued to challenge the line, leading to military hostilities in August 1981 and March 1986. A terrorist attack which killed two American soldiers and one Turkish civilian on 5 April 1986 was linked to Libya and prompted the U.S. to carry out retaliatory air strikes against targets in Libya ten days later.