The UN Security Council, at a historic summit meeting chaired by US President Barack Obama, unanimously approved a US-drafted resolution on Thursday calling on nuclear weapons states to scrap their deadly arsenals. It is the fifth time the Security Council has met at the level of heads of state since it was established in 1946 and the first time a U.S. president has chaired a meeting of the 15-nation elite panel. The resolution calls for stepped up efforts to prevent the spread of nuclear weapons, promote disarmament and "reduce the risk of nuclear terrorism."