unite nations dozens countries sign treaty ban nuclear weapons wednesday amid tensions north korea nuclear missile test although unite state britain france others boycott event annual unite nations gather world leaders treaty prohibition nuclear weapons enter force 90 days 50 countries ratify state due deposit ratification wednesday remain fifteen thousand nuclear weapons existence allow doomsday weapons endanger world children future u.n. secretary-general antonio guterres say open treaty sign early month north korea conduct sixth large nuclear weapons test u.s. president donald trump tell 193-member u.n. general assembly tuesday threaten unite state would totally destroy country 26 million people mock leader kim jong un rocket man treaty adopt july two-thirds 193 u.n. member state months talk unite state britain france others skip instead pledge commitment decades-old non-proliferation treaty aim prevent spread nuclear weapons weapons technology unite state britain france among nine countries believe nuclear weapons dozens state sign nuclear weapons ban treaty unite nations