VBIEDs (Vehicle Borne Improvised Explosive Device), otherwise known as car or truck bombs, are one of the most controversial weapons in the rebels' arsenal. The New York Times reported in September that an unwitting prisoner was used to drive a truck loaded with explosives toward a checkpoint near Idlib, believing it was part of a prisoner exchange.
This weapon is devastatingly simple. As the above video shows, insurgents simply fill vehicles with explosives, in this example including unexploded bombs, and drive them close to targets before detonating. In another case, a suicide car bomber killed at least 50 Syrian security men by exploding himself in the town of Sahl al-Ghab.
Both IEDs and VBIEDs were the scourge of the U.S. military in Iraq, and it may not be a coincidence that these weapons have now shown up in Syria. Some of the groups using these tactics supported the insurgency in Iraq: Jabhat al-Nusra, an al Qaeda-affiliated group that has claimed responsibility for a large number of these attacks, is perhaps the most prominent example.