Mk 77

The Mk 77 is an air-dropped incendiary bomb developed as the direct successor to napalm. It replaced the World War II-era Mark 47. The United States destroyed its inventory of Vietnam-era napalm in 2001, establishing the Mk 77 as the primary incendiary weapon in its inventory.

The weapon carries a fuel gel mixture composed of kerosene-based fuel with a lower concentration of benzene than previous incendiary munitions. The mixture includes an oxidizing agent and white phosphorus, making the ignited fuel difficult to extinguish. The Mk 77 is an unguided munition with limited accuracy, which generally precludes its use in urban terrain or areas where civilians are congregated. Multiple variants have been produced, including the Mod 4 and the Mod 5; the latter utilizes JP-4, JP-5, or JP-8 fuel combined with a thickener.

The Mk 77 is operated by the United States military, specifically by Marine Corps and Navy aviation units. It has seen combat use in several conflicts, including Operation Desert Storm, where it was dropped on oil-filled trenches. During the Afghan War, the weapon was used at the Battle of Tora Bora. In the 2003 invasion of Iraq, the Mk 77 was deployed against military targets, including Iraqi soldiers defending infrastructure such as bridges.

The use of aerial incendiary weapons is governed by the 1980 United Nations Convention on Certain Conventional Weapons Protocol III, which bans their use against civilian populations or military targets in civilian areas. The United States maintains a reservation to this protocol, allowing for the use of incendiaries against military objectives if such use is determined to result in fewer casualties or less collateral damage than alternative weapon systems. Deployment during the 2003 Iraq conflict led to diplomatic scrutiny following inaccurate information regarding the use of the Mk 77 provided to the United Kingdom Ministry of Defence.