What event marked the first time USAF personnel were attacked by terrorism, resulting in 19 Airmen's deaths?

The bombing of Khobar Towers is indeed recognized as a significant event in the history of the United States Air Force, as it marked the first time personnel were directly attacked by an act of terrorism, resulting in the tragic deaths of 19 Airmen. This incident occurred on June 25, 1996, when a truck bomb exploded near the towers in Dhahran, Saudi Arabia, which housed U.S. Air Force personnel stationed there as part of Operation Southern Watch. The attack not only highlighted the vulnerability of U.S. forces abroad but also underscored the evolving nature of warfare, which increasingly included acts of terrorism. The loss of life in this attack had profound implications for U.S. military policy and counter-terrorism strategies going forward.

The other options refer to different military operations and events that do not specifically involve acts of terrorism against U.S. Air Force personnel. Operation Desert Storm was a major conflict in the Gulf War, Operation Just Cause was a military intervention in Panama, and Operation Provide Hope was a humanitarian mission in response to a crisis in Somalia, none of which involved the direct terrorist attack on U.S. military personnel as evidenced by the bombing of Khobar Towers.