I guess there's an emergency security meeting at the U.N. today. Some countries like Japan are calling for sanctions. I don't think some of these measures will pass at all China and Russia has always blocked many of these measures that the US have supported. Besides that, I do believe there is a external conflict with the U.N. Security Council. The US won't denounce Israel for their actions against Palestinians while others do and because of that, they can't get across with the Iran situation.
We do not need North Korea to attack Japan or others countries at all. If they nuke Japan, Japan may have to start their military operations again. Lets not forget that the Chinese and Japanese hate each other. This is why we stablized Japan after World War II. We must protect Japan at any cost and not let this crisis become one of the catalysis to World War III.