Obama opts for nuclear option to revive world hope US president Barack Obama has used a speech in Berlin to call on Russia to revive nuclear talks with the aim of reducing the number of weapons deployed by one third, a step towards his goal of a nuclear-free world. Speaking yesterday in Berlin, where John F Kennedy famously gave a rousing Cold War speech, Mr Obama urged Russia to help build on the "New Start [Strategic arms reduction]" treaty that requires both countries to cut stockpiles of deployed nuclear weapons to 1,550 each by 2018. "After a comprehensive review I have determined that we can ensure the security of America and our allies, and maintain a strong and credible strategic deterrent, while reducing our deployed strategic nuclear weapons by up to one third," he said. "I intend to seek negotiated cuts with Russia to move beyond Cold War nuclear postures," he said at the Brandenburg Gate, which once stood alongside the Berlin Wall that divided the Communist East from the pro-market West. Mr Obama's vision of a "world without nuclear weapons" set out in a speech in Prague in 2009, three months into his presidency, earned him the Nobel Peace Prize. But his mixed results so far have fuelled criticism that the prize may have been premature. Experts said reducing the nuclear arsenal makes both strategic and economic sense. But Mark Fitzpatrick at the International Institute for Strategic Studies said Mr Obama faces major obstacles "including a recalcitrant Russia and a reluctant US senate." Shedding his jacket, the US president stood behind a bullet-proof pane and addressed a crowd of about 4,500, reading from paper because the teleprompter broke down. It was a stark contrast to the speech he delivered in the city in 2008, when he summoned a crowd of 200,000 to embrace his vision for US leadership. Whereas that speech soared with his ambition, this time he came to caution his audience not to fall into self-satisfaction. "Complacency is not the character of great nations," Obama insisted. Today, people often come together in places like this to remember history, not to make it. Today we face no concrete walls or barbed wire. Signalling a new effort to pick up his delayed environmental agenda, he also issued a call to tackle climate change, an issue he had promised to make a priority in his 2008 election campaign. "Peace with justice means refusing to condemn our children to a harsher, less hospitable planet," he said. He said the US has expanded renewable energy from clean sources and is doubling fuel efficiency in cars. But he said that without more action by all countries, the world faces a grim alternative of more severe storms, famine, floods, vanishing coastlines and displaced refugees. "This is the future we must avert," he said. This is the global threat of our time. Among those in the audience, Doro Zinke, president of the Berlin-Brandenburg trade union federation, said she heard nothing unexpected in the speech. "I think he's really got to deliver now," she said. But others gave him credit for just coming to Berlin, five years into his presidency. "The most important message here was that he came to Berlin and spoke to us and the world," said Catharina Haensch, a Berliner born in the East. Even if it looks like he isn't able to fulfil all of his promises, you've got to keep on hoping.