Robert Gates, the US defence secretary, claimed that neither the US nor Israel felt the need to rush into precipitate action despite fears that sanctions will do little to convince Iran to give up its nuclear programme. "I think that everybody agrees we have some more time, including the Israelis, and we will just continue to work it," Mr Gates said after a meeting with his Nato counterparts in Brussels "Most people believe that the Iranians could not really have any nuclear weapons for at least another year or two. I would say the intelligence estimates range from one to three years." The assessment came as Mahmoud Ahmadinejad, the Iranian president, laughed off the latest round of sanctions imposed on his country this week by the United Nations Security Council. Mr Ahmadinejad accused President Barack Obama, of "immaturity" and a failure to understand the world. "I think President Obama has made a big mistake," he said. "He knows the resolution will have no effect. Very soon he will come to understand that he has not made the right choice and he has blocked the way to having friendly ties with the Iranian people." Speaking during a trip to China to view the Iranian stall at the World Expo fair in Shanghai, Mr Ahmadinejad was more cautious about criticising his hosts, who backed the resolution.