Don't Let Kim Jong Un Blow Atomic Smoke in Your Eyes

North Korea would like nothing more than for the U.S. and its allies to hyperventilate over the North's third test of a nuclear device. Indeed, with two satellite-cum-missile launches and one nuclear test during his first year in power, North Korean leader Kim Jong Un has already displayed an appetite for foreign-policy brinksmanship that goes beyond the political need to show his people that he's large and in charge.

That said, there is good reason for the U.S. to remain calm and carry on, building a united front with the new governments in South Korea and Japan, trying to bring the Chinese along and then strengthening and refining sanctions through the United Nations.

First and most important, North Korea is unlikely to abandon its provocative behavior. In fact, tighter UN sanctions will likely lead to "high-level secondary and third measures," as the Korean Central News Agency put it in an official statement. Two tunnels were being prepared for nuclear tests, and only one has just been used (though it's possible that the other was a decoy). The North will not give up its nuclear weapons, which it sees as the best insurance for regime survival; more tests are needed to create a reliable warhead that can be mounted on missiles. It seeks recognition as a nuclear state and peace talks with the U.S. on that basis.

China's real fears about the destabilizing effect of the North's nuclear quest are still secondary to its fears about a weakened ally, not least the strategic and humanitarian consequences of that ally's collapse. In their eyes, the North is alternately a problem to be managed or a card to be played in Northeast Asia's evolving power struggle: As one influential Chinese pundit recently suggested, in a dark analysis that linked the territorial spat between Japan and China to tensions on the Korean peninsula, "If America wants to play the Japanese card against China, then China needs to play the North Korean nuclear card on America." China may not be happy about Kim Jong Un's radioactive gambit, but it will strive, as it has in the past, to water down new sanctions and go along with the bare minimum.

Here's how the U.S. can raise the bar for the Chinese: First, don't hype President Barack Obama's description of the North's nuclear test as a "threat to U.S. national security." That may be true, but it plays into the North's rhetoric of the U.S. as its "enemy." Instead, emphasize that the North's behavior violates the expressed will of the United Nations Security Council and undermines the global nonproliferation regime -- That's easier for China, a P-5 member, to support. Second, forge the strongest possible united front with the South Koreans and the Japanese. Third, make clear to the Chinese that North Korea's WMD plans will make it imperative for the U.S. to expand its missile defense umbrella over Japan and South Korea and its overall military and security presence. Fourth, hint at the possibility of additional U.S. financial sanctions outside the UN framework that could hit Chinese firms with a U.S. presence. China needs to know that it will pay a growing price for in effect enabling North Korea's destabilizing actions.

Still, if sanctions are unlikely to change North Korea's behavior, why pursue them? Because they not only slow down the North's pursuit of weapons of mass destruction, but can also curb its mutually beneficial ties with Iran, Syria, Cuba and other unsavory regimes. That's why North Korea put up a howl about the prospect of ship searches contained in the tighter sanctions passed last month. The U.S. should also discourage Egypt, Libya, Yemen and other past Middle Eastern buyers of North Korean weapons from pursuing future transactions.

But sanctions without diplomacy are just the sound of one hand slapping. To get out of the current tit-for-tat stalemate, the U.S. needs to abandon its pre-condition that the North give up its nuclear weapons program before the U.S. will negotiate a permanent peace treaty. And it needs to pursue sanctions that focus on the North's dangerous behavior, not on discouraging its healthy commercial and cultural engagement with the outside world.

This column does not necessarily reflect the opinion of Bloomberg View's editorial board or Bloomberg LP, its owners and investors.