During his recent visit to South Korea, Deputy Secretary of Defense Paul Wolfowitz announced Washington’s intention to “reposition” some of its military forces stationed in South Korea. Currently, most U.S. troops are deployed in the northern part of the country, between the capital, Seoul, and the Demilitarized Zone that separates South Korea from communist North Korea. The redeployment would entail moving those forces farther south.

Wolfowitz offered only a vague justification for such a move, contending that repositioning forces would make them more effective in meeting the threat posed by North Korea. That is a curious argument. Since the end of the Korean War in 1953, the principal rationale for stationing the troops near the DMZ has been that they would serve as a tripwire in case of a North Korean attack, guaranteeing U.S. involvement in any conflict. North Korea, knowing that it would then face war not only with South Korea but also with the United States, would be deterred from taking such a reckless gamble.

Why is the Bush administration proposing to abandon the long-standing tripwire function of U.S. forces in South Korea? There is one unsettling possibility: The administration is considering a preemptive military attack on North Korea’s nuclear installations and wants to move American troops out of harm’s way. Even most hawkish U.S. experts on Korea concede that if the United States did launch such an attack, the North would likely respond with an intense artillery and missile barrage of the Seoul metropolitan area and, possibly, with a ground attack through the DMZ. American troops stationed between Seoul and the DMZ could easily end up being dead tripwire forces.

True, Bush administration officials have stated that they want to solve through diplomacy the crisis created by North Korea’s resumption of its nuclear weapons program. But those same officials have stressed that all options, including the use of military force, remain on the table. When South Korean President Roh Moo-hyun came to the United States in May, he sought an assurance that the controversial doctrine of preemptive war embedded in the administration’s national security strategy would not apply to North Korea.. U.S. officials rebuffed his request.

Indeed, the national security strategy document approved in September 2002 clearly would seem to apply to the North Korean situation. “We must be prepared to stop rogue states and their terrorist clients before they are able to threaten or use weapons of mass destruction against the United States and our allies and friends,” the document affirmed. The administration’s policy on combating weapons of mass destruction, adopted in December 2002, stated the point even more succinctly, emphasizing that the United States would not “permit the world’s more dangerous regimes” to pose a threat “with the world’s most destructive weapons.” Nuclear weapons in the hands of secretive, Stalinist North Korea fill that category.

Even if one takes the Bush administration at its word that it wants to settle the crisis through diplomacy, it begs a crucial question: What does the United States do if diplomacy (or diplomacy combined with economic pressure) fails to induce North Korea to abandon its nuclear program?. Is the administration prepared to live with a North Korea armed with nuclear weapons? The statement issued by Bush and Japanese Prime Minister Junichiro Koizumi following their recent summit suggests otherwise. The two leaders stated bluntly that they “would not tolerate” a nuclear armed North Korea.

If diplomacy fails, it is not clear how that result can be prevented except through military force. The Bush administration may not be committed to such a course as yet, but in deciding to move U.S. forces away from the DMZ, it is creating a precondition for pursuing that option. South Koreans, who know how horribly their country would suffer if the United States launched preemptive strikes on the North, now have reason to be very, very nervous.