U.N. Security Council Resolution 2139 of Feb. 22, 2014, ordered all parties to the conflict in Syria to end the use of barrel bombs and other weapons in populated areas. In spite of that, both the Syrian and the Iraqi governments continue using them against civilians.

Human rights groups have characterized them as weapons of terror and illegal under international conventions.

Barrel bombs are a type of improvised explosive device (IED), sometimes described as "flying IED," typically made from a barrel that has been filled with high explosives, shrapnel, oil and chemicals and then dropped from a plane or a helicopter. They are cheap to produce, so they are used extensively in conflicts such as Syria and Iraq.