Chairman of the US Joint Chiefs of Staff Adm. Mike Mullen said Thursday that the consequences of Iran acquiring a nuclear weapon would be "calamitous" and that major powers must join hands and act to prevent it, Reuters reported. Speaking a day after Iran test-launched a long-range ballistic missile, Mullen told the US Senate Foreign Relations Committee, "I'm one who believes that Iran getting a nuclear weapon is calamitous for the region and for the world." "It then, in my view, generates neighbors who feel exposed, deficient and then develop or buy the capability themselves," he continued. "The downside, potentially, is absolutely disastrous," alluding to the possibility of a nuclear arms-race in the Middle East. "Major leaders, internationally, have got to come together to arrest this growth or the long-term downside for the people in the world is really, really tragic and drastic," Mullen said. On Monday, US President Barack Obama expressed his wish to start talks with Teheran in the near future, following Iranian presidential elections scheduled for June. He also set a tentative timetable for his diplomatic efforts, stating that the US would evaluate progress by the end of 2009.