sentences:  Since the Gulf War, the U.S. had a continued presence of 5,000 troops stationed in Saudi Arabia – a figure that rose to 10,000 during the 2003 conflict in Iraq.Operation Southern Watch enforced the no-fly zones over southern Iraq set up after 1991, and the country's oil exports through the shipping lanes of the Persian Gulf are protected by the US Fifth Fleet, based in Bahrain.The continued presence of U.S. troops in Saudi Arabia was one of the stated motivations behind the September 11 attacks, as well as the Khobar Towers bombing.