Obama in push for 'world without nuclear weapons'

US President Barack Obama says he is pushing for "a world without nuclear weapons", making direct appeals to North Korea and Iran. He also pledged to work with Russia and China, speaking ahead of a summit in Seoul aimed at reducing the risk of nuclear terrorism. He emphasised the US's unique position to seek change but said "serious sustained global effort" was needed. The meeting is being attended by representatives from some 50 countries. Speaking to students at Hankuk University, Mr Obama reiterated the commitment of the US as ''the only nation to have ever used nuclear weapons'' to reducing its nuclear arms stockpile. He also spoke, he said, as a father who did not want to see his daughters growing up in a world with nuclear threats, a comment which drew applause from his student audience. The US president said he was looking forward to meeting newly-elected Russian President Vladimir Putin in May to discuss further nuclear arms cuts. Mr Obama would seek to follow on from the New Start (Strategic Arms Reduction Treaty) pact he struck in 2010 with outgoing Russian leader Dmitry Medvedev in 2010, he said. The New Start deal agreed between Washington and Moscow was intended to replace its lapsed predecessor, Start. It trims US and Russian nuclear arsenals to 1,550 deployed nuclear warheads - a cut of about 30% from a limit set previously. The treaty would also allow each side visually to inspect the other's nuclear capability, with the aim of verifying how many warheads each missile carries. In addition, there will be legally binding limits on the number of warheads and missiles that can be deployed on land, on submarines, and on bombers, at any one time.