The US and a few other countries have been cautious in confirming exactly what North Korea achieved in its claimed nuclear test. I'm torn between a cynical view of what North Korea is really capable of achieving scientifically and a REALLY cynical view of what a success would mean for the world.
The size of the seismic impact seems a bit smaller than some would expect for a typical "freshman gadget" attempt. A quick google for "seismic nuclear reaction" produces some links that indicate the duration of the strongest portion of the seismic shock produced by the explosion should be a good indicator of whether a true nuclear reaction was achieved or if conventional high explosives were detonated.
The cynic in me looks at videotape from North Korea and wonders how an economy incapable of generating enough electricity to light the country after dark could sustain research and manufacturing facilities capable of doing fission research and enrichment. Yes, they very well could be obtaining material from Pakistan, our "ally" in the War on Terror (TM) or stolen material from the former Soviet Union. You still have to put the weapons-grade material in a gadget and figure out how to trigger a detonation that produces critical mass. Have you seen video of anything in North Korea. The country looks like the land that the 1950s forgot. Black and white CRT monitors in nuclear facilities, not a single color flat-screen in sight. Are we sure ENIAC hasn't been stolen from a museum somewhere? Has the demand for vacuum tubes suddenly skyrocketed?
The REAL cynic in me assumes North Korea did actually pull off a nuclear detonation. Now what?
The first concern that comes to mind if they succeeded still involves those 1950-era facilities. What do you think the chances are of some poorly trained North Korean nuclear engineer making a mistake at a refining facility or reactor and producing another Chernobyl scale eco-disaster? North Korea's closed society / house of mirrors makes Russia circa-1986 look positively wide open in comparison. If North Korea makes a nuclear mistake, do you think they'll tell anyone before DAYS / WEEKS of radiation are released or before the first 500,000 North Koreans drop dead from the radiation?
The second concern that comes to mind if they succeeded is the lack of options the United States has in dealing with the consequences. We've already crippled our threat deterrent by previously stating nuclear development is unacceptable, doing nothing to stop it, and having nothing to say after they achieved the goal. At the same time, we have spent 3 years and over $330 billion undermining our actual military capacity to take any action chasing phantom WMDs in a situation that has now trapped us in the middle of a civil war. Ask any state Governor or state National Guard head and they'll tell you, WE HAVE NOTHING LEFT IN THE TANK.
A third concern is the complete lack of insight and communication about / to North Korea and the rest of the world. This is slightly chauvinistic from an American / Western standpoint, but virtually every country on the planet has SOMEONE in their foreign affairs office that can speak English clearly and with proper grammar and idiomatic phrases. Have you heard ANYONE speaking on behalf of North Korea that fits that description? That means not only that WE know nothing about their inner circle, it means no one in their inner circle has probably gotten out of the country much to learn anything about the rest of the world. The government and citizens of North Korea might as well be from another galaxy in terms of their ability to understand the world around them.
So what's left? Sanctions? Against a country that is already starving its people? Against a country that disappears off the satellite view after dark? I thought the failure of sanctions was why we invaded Iraq. Why will sanctions that "can never work" in one situation produce any benefits in another?
I guess when you only have a hammer left in your toolbox, every problem's a nail.
