The Mark 77 bomb (MK-77) is a U.S. 750-pound (340 kg) air-dropped incendiary bomb carrying 110 U.S. gallons (416 L; 92 imp gal) of a fuel gel mix which is the direct successor to napalm. The MK-77 is the primary incendiary weapon currently in use by the United States military. Instead of the gasoline, polystyrene, and benzene mixture used in napalm bombs, the MK-77 uses kerosene-based fuel with a lower concentration of benzene. The Pentagon has claimed that the MK-77 has less impact on the environment than napalm. The mixture reportedly also contains an oxidizing agent, making it more difficult to put out once ignited, as well as white phosphorus. The effects of MK-77 bombs are similar to those of napalm. The official designation of Vietnam War-era napalm bombs was the Mark 47. Use of aerial incendiary bombs against civilian populations, including against military targets in civilian areas, was banned in the 1980 United Nations Convention on Certain Conventional Weapons Protocol III. However the United States reserved the right to use incendiary weapons against military objectives located in concentrations of civilians where it is judged that such use would cause fewer casualties and/or less collateral damage than alternative weapons.