Source: N. Korea may be preparing for new nuclear test - CNN.com
CNN reports: "The official, who is not authorized to speak on the record, told CNN that Washington has 'indications' that North Korea may be planning another test, which would be its third since 2006. The official would not provide any details, however."

Comment: And if they do, the U.N. will tighten sanctions even more. See, it's important that when the U.N. imposes sanctions on a country that they be very loose and easily evaded. That way, if the country continues to defy the will of the great powers, they can then tighten the sanctions and say that they have done something even when they didn't. The only country here that really matters is China, whose trade ties with the North have only increased over the period of sanctions, so they have leverage, if they want to use it, though they probably don't. So, with a permanent member of the Security Council in their corner, North Korea can pretty much test as many weapons as they want and no other country, not even the U.S., will risk actual war to stop them. Still, there is always room for miscalculation, so the danger is still very real.