Argument: Enforcing a nuclear test ban, not detecting tests, is the issue
Paula Desutter. "The Test Ban Treaty Would Help North Korea". Wall Street Journal. June 1, 2009: "Verification has two purposes: detection and deterrence. If you can't detect, you can't deter. But even if you can detect, you may not be able to deter.
With regard to seismic detection, North Korea is a best-case scenario. It is small, its known test site is granite, and it is not a seismically active region. In 2006 we collected noble gases to confirm the explosion was nuclear. Moreover, North Korea announces its tests. Detection of announced tests cannot be sold as proof of verifiability.
As for deterrence, it's a simple concept: convince others that the cost of taking an action you wish to prevent is far greater than any benefits. At a minimum, violators should not benefit from their violation.
The Obama administration's special envoy for North Korea, Stephen Bosworth, has been touring the region warning of "dire consequences" if North Korea tests. Strong words, but likely empty of substance. Will we bomb their nuclear sites? Unlikely, even if we knew where most of them were. Trade restrictions? North Korea has nothing to sell to non-rogue states. Stop food aid? Americans don't want to punish the starving slave-citizens of North Korea for actions over which they have no influence. In fact, we've taught North Korea since the early 1990s that crime pays.
The Clinton administration had declared its policy goal with respect to North Korea to be "regime change." North Korea then blatantly violated the Nuclear Nonproliferation Treaty (NPT). The U.S. was in the lead-up to an NPT review conference where the goal was the indefinite extension of that treaty. The arms controllers saw North Korea's violation as threatening a successful review conference. So the Clinton administration had direct negotiations resulting in the 1994 Agreed Framework. North Korea was given heavy fuel oil, food and offered two light-water nuclear reactors at no cost. All it had to do was freeze plutonium reprocessing facilities at Yongbyon until new reactors were near completion, at which point it would have to dismantle Yongbyon. The new Clinton policy goal: regime stability in order to ensure implementation of the agreed framework. So by violating the NPT, North Korea got the most powerful country in the world to abandon regime change and declare that it was in our interest to keep the regime in place. Crime paid."