The Bombings
At around 6:20 a.m., a yellow Mercedes-Benz truck drove to Beirut International Airport, where the 1st Battalion 8th Marines under the 2nd Marine Division had set up its local headquarters. The truck was not the water truck they had been expecting, but a hijacked truck carrying explosives. The truck turned onto an access road leading to the compound and circled a parking lot. The driver then accelerated and crashed through a barbed wire fence around the parking lot, passed between two sentry posts, crashed through a gate and drove toward the lobby of the marine headquarters. The sentries at the gate were operating under rules of engagement which made it very difficult to respond quickly to the truck. Sentries were ordered to keep their weapons at condition four (no magazine inserted and no rounds in the chamber). By the time the two sentries were able to engage, the truck was already heading towards the building's entry way, armed.
The suicide bomber reached the entry way and detonated his explosives, which were equivalent to 5,400 kg (12,000 pounds) of TNT. The force of the explosion collapsed the four-story building into rubble, crushing many inside. According to Eric Hammel in his history of the Marine landing force,
"The force of the explosion initially lifted the entire four-story structure, shearing the bases of the concrete support columns, each measuring fifteen feet in circumference and reinforced by numerous one-and-three-quarter-inch steel rods. The airborne building then fell in upon itself. A massive shock wave and ball of flaming gas was hurled in all directions."
The explosive mechanism was a gas-enhanced device, probably consisting of bottled propane, butane, hexane or acetylene, placed in proximity to a conventional explosive such as primacord, all of which are readily available on the retail market. The bomb was carried on a layer of concrete covered with a slab of marble to direct the blast upward. Despite the lack of sophistication and wide availability of its component parts, a gas-enhanced device can be a lethal weapon. These devices are similar to fuel-air or thermobaric weapons, explaining the large blast and damage.
About two minutes later, a similar attack occurred against the barracks of the French 3rd Company of the 1st Parachute Chasseur Regiment, 6 km away in the Ramlet al Baida area of West Beirut. Another suicide bomber drove his truck down a ramp into the 'Drakkar' building's underground parking garage and detonated his bomb, leveling the eight-story building and killing 58 French soldiers. Many of the soldiers had gathered on their balconies moments earlier to see what was happening at the airport It was the worst military loss for France since the end of the Algerian War in 1962.
Read more about this topic: 1983 Beirut Barracks Bombing