Car bombs can be roughly divided into two main categories: those used primarily to kill the occupants of the vehicle (often as an assassination) and those used as a means to kill, injure or damage people and buildings outside the vehicle. The latter type may be either parked (the vehicle disguising the bomb and allowing the bomber to get away) or the vehicle might be used to deliver the bomb (often as part of a suicide bombing).
It is commonly used as a weapon of terrorism or guerrilla warfare to kill people near the blast site or to damage buildings or other property. Car bombs act as their own delivery mechanisms and can carry a relatively large amount of explosives without attracting suspicion; in larger vehicles and trucks, weights of around 7,000 pounds (3,200 kg) or more have been used, for example, in the Oklahoma City bombing. Car bombs are activated in a variety of ways, including opening the vehicle's doors, starting the engine, depressing the accelerator or brake pedals or simply lighting a fuse or setting a timing device. The gasoline in the vehicle's fuel tank may make the explosion of the bomb more powerful by dispersing and igniting the fuel.
Car bombs are effective weapons as they are an easy way to transport a large amount of explosives to the intended target. A car bomb also produces copious shrapnel, or flying debris, and secondary damage to bystanders and buildings. In recent years, car bombs have become widely used by suicide bombers.
Defending against a car bomb involves keeping vehicles at a distance from vulnerable targets by using roadblocks and checkpoints, Jersey barriers, concrete blocks or bollards, metal barriers, or by hardening buildings to withstand an explosion. Since the height of the Provisional Irish Republican Army (PIRA) campaign in 1991, the entrance to Downing Street has been closed, preventing the general public from getting near Number 10. Where major public roads pass near buildings, road closures may be the only option (thus, for instance, in Washington, D.C. the portion of Pennsylvania Avenue immediately in front of the White House is closed to traffic). Historically these tactics have encouraged potential bombers to target "soft" or unprotected targets, such as markets.
In the Syrian Civil War, and Iraq, the car bomb concept was modified so that it could be driven and detonated by a driver, but armoured to withstand incoming fire. The vehicle would be driven to its target area, in a similar fashion to a kamikaze plane of WW2. These were known by the acronym SVBIED (from Suicide Vehicle Borne Improvised Explosive Device) or VBIEDs. This saw generally civilian cars with armour plating added, that would protect the car for as long as possible, so that it could reach its intended target. Cars were sometimes driven into enemy troop areas, or into incoming enemy columns. Most often, the SVIEDs were used by ISIS against Government forces, but also used by Syrian rebels (FSA and allied militias) against government troops.
The vehicles have become more sophisticated, with armour plating on the vehicle, protected vision slits, armour plating over the wheels so they would withstand being shot at, and also in some cases, additional metal grating over the front of the vehicle designed to activate rocket propelled grenades before hitting the actual surface of the vehicle.
In some cases trucks were also used, as well as cars. They were sometimes used to start an assault. Generally the vehicles had a large space that would contain very heavy explosives.
In some cases, animal drawn carts with improvised explosive devices have been used, generally either mules or horses.
Tactically, a single vehicle may be used, or an initial "breakthrough" vehicle, then followed by another vehicle.
While many car bombs are disguised as ordinary vehicles, some that are used against military forces have improvised vehicle armour attached to prevent the driver from being shot when attacking a fortified outpost.
Car bombs are preceded by the 16th century hellburners, explosive-laden ships which were used to deadly effect by the besieged Dutch forces in Antwerp against the besieging Spanish. Though using a less refined technology, the basic principle of the hellburner is similar to that of the car bomb.
The first reported suicide car bombing (and possibly the first suicide bombing) was the Bath School bombings of 1927, where 45 people, including the bomber, were killed and half of a school was blown up.
Mass-casualty car bombing, and especially suicide car bombing, is currently a predominantly Middle Eastern phenomenon. The tactic was first introduced to the region by the Zionist paramilitary organization Lehi, who used it extensively against Palestinian and British military targets; it was subsequently taken up by Palestinian bombers as well. The tactic was widely used in the Lebanese Civil War by the Islamic fundamentalist group Hezbollah. A notable suicide car bombing was the 1983 Beirut barracks bombing, when two simultaneous attacks killed 241 U.S. Marines and 58 French military personnel. The perpetrator of these attacks has never been positively confirmed. In the Lebanese Civil War, an estimated 3,641 car bombs were detonated.
While not an adaptation of a people-carrying vehicle, the WW2 German Goliath remote control tank, shares many parallels with a vehicle-based IED. It approached a target (often another tank) at some speed, and then exploded, destroying itself and the target. It was armoured so that it could not be destroyed en route. However, it was not driven by a person, instead operated by remote control from a safe distance. It was effectively an armoured suicide drone.
As a booby trap
TSA officers view the post-blast remains of a Chrysler Neon after an explosive was detonated inside it during training.
Car bombs and detonators function in a diverse manner of ways and there are numerous variables in the operation and placement of the bomb within the vehicle. Earlier and less advanced car bombs were often wired to the car's ignition system, but this practice is now considered more laborious and less effective than other more recent methods, as it required a greater amount of work for a system that could often be quite easily defused. While it is more common nowadays for car bombs to be fixed magnetically to the underside of the car, underneath the passenger or driver's seat, or inside of the mudguard, detonators triggered by the opening of the vehicle door or by pressure applied to the brakes or accelerating pedals are also used.
Bombs operating by the former method of fixation to the underside of the car more often than not make use of a device called a tilt fuse. A small tube made of glass or plastic, the tilt fuse is not dissimilar to a mercury switch or medical tablet tube. One end of the fuse will be filled with mercury, while the other open end is wired with the ends of an open circuit to an electrical firing system. Naturally, when the tilt fuse moves or is jerked, the supply of mercury will flow to the top of the tube and close the circuit. Thus, as the vehicle goes through the regular bumping and dipping that comes with driving over a terrain, the circuit is completed and the bomb or explosive is allowed to function.
As a safety mechanism to protect the bomber, the placer of the bomb may rig a timing device incorporated with the circuit to activate the circuit only after a certain time period, therefore ensuring the bomber will not accidentally activate the bomb before he or she is able to get clear of the blast radius.
Prior to the 20th century, bombs planted in horse carts had been used in assassination plots, notably in the unsuccessful "machine infernale" attempt to kill Napoleon on 24 December 1800.
PIRA Chief of Staff Seán Mac Stíofáin defines the car bomb as both a tactical and a strategic guerrilla weapon. Strategically, it disrupts the ability of the enemy government to administer the country, and hits simultaneously at the core of its economic structure by means of massive destruction. From a tactical point of view, it ties down a large number of security forces and troops around the main urban areas of the region in conflict.
1927: The Bath School disaster -- Andrew Kehoe used a detonator to ignite dynamite and hundreds of pounds of pyrotol which he had secretly planted inside a school. As rescuers started gathering at the school, Kehoe drove up, stopped, and detonated a bomb inside his shrapnel-filled vehicle, killing himself and the school superintendent, and killing and injuring several others. In total, Kehoe killed 44 people and injured 58 making the Bath School bombing the deadliest act of mass murder in a school in U.S. history. It is possibly the first suicide car bombing in history.
The Basque separatist group Euskadi Ta Askatasuna (ETA) carried out at least 80 massive car bomb attacks in Spain during the last decade before putting its activities on hold in 2011.
Freelance terrorist Carlos the Jackal claimed responsibility for three car bomb attacks on French newspapers accused of pro-Israeli bias during the 1970s.
Cleveland Irish mobster Danny Greene frequently used car bombs against his enemies, beginning in 1968. Afterwards, they also began to be used against Greene and his associates. The use of car bombs in Cleveland peaked in 1976, when 36 bombs exploded in the city, most of them car bombs, causing it to be nicknamed "Bomb City." Several people, including innocent bystanders, were killed or wounded. Greene himself was finally killed in a car bomb explosion on October 6, 1977.
The German Red Army Faction occasionally used car bombs, such as in an unsuccessful attempt to attack a NATO school for officers in 1984.
Suicide car bombs were a regular feature against Israel in the 1982 Lebanon War which lasted from 1982 until Israel's withdrawal in 2000. The bombing campaign was waged by several groups, most prominently Hezbollah.
On 26 February 1993, Islamist terrorists led by Ramzi Yousef detonated a Ryder truck filled with explosives in the parking garage of the World Trade Center in New York City. Yousef's plan had been to cause one of the towers to collapse into the other, destroying both and killing thousands of people. Although this was not achieved, six people were killed, 1,402 others injured, and extensive damage was caused.
Southeast Asia-based militant Islamist group Jemaah Islamiyah utilized car bombs in their campaigns during the early 2000s, the most prominent being the 2002 Bali bombings, which killed 202 people.
On 30 June 2007, a Jeep Cherokee loaded with propane tanks crashed into the entrance of Glasgow International Airport. The vehicle caught fire, but failed to detonate. As a result, there were no injuries from the attack itself apart from the driver, who died of his injuries several weeks later, and one passenger who was severely burned, although several bystanders were injured in restraining the two. The attackers appear to have been Muslims unaffiliated with any organization who were disgruntled about the War on Terror. Thirty-six hours earlier, two bombs had also been found in a vehicle in London, although the police reported that the bombs were incomplete and could not have exploded.
The Tamil Tigers of Sri Lanka frequently made use of car bombs during that country's civil war in a campaign which lasted from 1976 until the group's defeat in 2009.
On 11 December 2010, (2010 Stockholm bombings) - a car bomb exploded in central Stockholm in Sweden, slightly injuring two bystanders. Twelve minutes later, an Iraqi-born Swedish citizen accidentally detonated six pipe bombs he was carrying, but only one exploded. The bomber was killed but there were no other casualties. It is believed that the attacks were the work of homegrown terrorists who were protesting Sweden's involvement in the war in Afghanistan and the publication in Sweden of cartoons depicting Muhammad.
Although it has never been officially acknowledged, the American CIA has occasionally been accused of being behind car bombings. One such attack was the failed assassination attempt on Grand Ayatollah Mohammad Hussein Fadlallah in the Beirut car bombing on 8 March 1985. Although there has been widespread speculation of CIA involvement, this has never been proven conclusively.
Since the beginning of the U.S.-led war in Afghanistan in 2001, the Taliban have often employed vehicular explosives against enemy targets. This has included not just cars and trucks but even bicycle bombs.
A 2005 car bombing in Iraq, in which a second car bomb was detonated while US forces were investigating the scene of an earlier such blast, resulting in 18 casualties.
The Iraqi insurgency. An estimated 578 car bombs were detonated in Iraq between June 2003 and June 2006. Car bombs continue to be commonly used.