After a week including a nuclear test and several missile trials America has warned North Korea it will not accept it becoming a nuclear state.Speaking at an Asian defence conference in Singapore the message, delivered by US Defence Secretary Robert Gates, represents a hardening of the US position. “We will not stand idly by as North Korea builds the capability to wreak destruction on any target in the region or on us. At the end of the day, the choice to continue as a destitute international pariah or chart a new course is North Korea’s alone to make. The world is waiting,” he said. Gates met with senior Chinese figures at the meeting who called for the international community to cool it on North Korea lest the war of words escalate into something more dangerous. A US delegation arrives for an Asian tour next week when North Korea is likely to be at the top of the agenda. By then Washington says Pyongyang may have moved a new intercontinental ballistic missile ready for testing from near the capital to the east coast, with a range capable of hitting Japan, Alaska or major bases like Okinawa or Hawaii.