US President Barack Obama is to chair a United Nations Security Council meeting on nuclear disarmament on September 24, dpa cited US Ambassador Susan Rice as announcing today. It is the first time that a US leader will lead a debate in the political body, and Rice's announcement came a day after the US took over the rotating presidency of the council. The 15-nation council has never held a session on nuclear disarmament since its formation in 1945. Obama will also lead a discussion on the Nuclear Non-Proliferation Treaty. Rice said nuclear disarmament was a "pressing issue" for the Obama administration. Obama had called for a world free of nuclear weapons after he took over The White House. Rice on Wednesday also made public the council's monthly programme of work. The UN General Assembly session opens in mid-September, and government leaders from 192 countries that are UN members will attend the meetings of the assembly as well as the council.