Early in the morning of October 23, 1983, a Mercedes truck arrived at the Beirut International Airport, which was housing a battalion of United States Marines at the time, blew up the barracks and killed 299 US service members. A second attack minutes later killed 58 French paratroopers across town. The bombing, taking place in the midst of the Lebanese Civil War, was one of the first carried out by elements of what would soon become Hezbollah.The yellow truck that slammed into the ground floor of the Marine Corps barracks that day was packed with gas canisters and explosives creating a blast with the equivalent explosive power of 20,000 pounds of TNT. The bed of the truck was lined with concrete, a design intended to direct the blast upwards into the building, which was literally lifted off the ground before falling back upon itself and its inhabitants.RELATED:Syria to air confession of 'Israeli spy' in Mughniyeh hit Report: Mughniyeh among suspects behind Hariri murder The attack represented the single deadliest day for US Marines since the Battle of Iwo Jima in World War II. The French had not seen such devastation since the Battle of Algiers two decades earlier.In the weeks before the bombing, US forces in Lebanon, part of a multi-national peacekeeping force sent to oversee the withdrawal of Palestinian Liberation Organization personnel from the country, had become more aggressive in carrying out its mission. Following an agreement by Israel to withdraw from the country in mid-1983, attacks on US forces increased. The Marine barracks at the Beirut airport came under sustained artillery fire from Shi’ite and Druse militias.The shelling carried out in retaliation by US naval forces against Shi’ite and Druse in mid- to late-September began causing a number of civilian casualties. The US forces had also begun directly supporting the Lebanese army with naval gunfire in the weeks before the barracks bombing. Analysts and observers, including the commander of the Beirut Marine base at the time, later pointed to those attacks as destroying the perception of neutrality enjoyed by international forces up until that point."American support removed any lingering doubts of our neutrality, and I stated to my staff at the time that we were going to pay in blood for this decision," US Marine Colonel Timothy J. Geraghty later wrote.But while Shi’ite Lebanese elements carried out the attack in retaliation for perceived increased US role in the Lebanese Civil War, other actors were also involved. Less than one month before the bombings, US intelligence had intercepted a cable from Tehran to Iran’s ambassador in Syria instructing him to attack the US Marines in Beirut. That intercept was never relayed to American forces on the ground before the attack took place. Although no group has ever made a serious claim of responsibility for the attack, perpetrators were later fingered. The actors that carried out the deadly bombings were elements that two years later would be central and founding members of Hezbollah, a group well-known to be funded, armed and trained by Iran.One of the central actors in the bombing, Imad Mughniyeh, was secretly indicted several years later in the United States for his role. Mughniyeh, who would later become known as an arch-terrorist of sorts, has been tied to and indicted in relation to some of the largest terror attacks on Jews and Americans carried out prior to September 11, 2001.The Hezbollah terrorist was indicted in relation to the 1992 bombings of the Israeli embassy in Buenos Aires and the 1994 bombing of a Jewish center in the city, two attacks that killed over 100 people. In addition, he was tied to the 1996 bombing of another US military barracks, this time at the Khobar Towers in Saudi Arabia, which killed 19 US military personnel.In 2008, Mughniyeh was assassinated in Damascus by a bomb placed in the headrest of his car, an attack attributed to Israeli intelligence by foreign media.If the goal behind the Beirut bombs was to drive US forces out of Lebanon, Mughniyeh and his Shi’ite Lebanese and Iranian backers’ succeeded. Despite strong statements suggesting otherwise at the time from US president Ronald Reagan, backed up by a high profile visit from then-US vice president George H.W. Bush, the United States Marines redeployed offshore less than two months later.