The Fissile Material Cutoff Treaty (FMCT) is a proposed international treaty to prohibit the further production of fissile material for nuclear weapons or other explosive devices. The treaty has not been negotiated and its terms remain to be defined. According to a proposal by the United States, fissile material includes high-enriched uranium and plutonium (except plutonium that is over 80% Pu-238). According to a proposal by Russia, fissile material would be limited to weapons-grade uranium (with more than 90% U-235) and plutonium (with more than 90% Pu-239). Neither proposal would prohibit the production of fissile material for non-weapons purposes, including use in civil or naval nuclear reactors.