Hi
Obama is more than willing to use anything that he can find as a distraction to his inability to deal effectively with the current financial situation. Political standard, money problems at home, find an external enemy, try and use that to minimize the money issues.
As to North Korea being a danger, they truly are. Their leaders feel that they can do what they want, depending on China to back their play. To a very large extent this is the case, else the South Koreans would have removed that dictatorship a long time ago.
Are they stupid enough to launch? There is a danger in the 10% to 15% range that they might. If they launch conventional warheads, China will back them. If they launch nukes, China will be forced to let us remove the North Korean government. That by the way will not be an easy fight, they have one of the largest armies on the planet, and it is reasonably well equipped.