While the United States prepares for war across the Atlantic, a dangerous, hostile regime across the Pacific is sending nearly daily signals that it finds America's policies unacceptable and may well be willing to use force to change them. With most of America's attention and effort focused to the east, a window of opportunity is created in East Asia, where our forces are clearly not adequate to deal with the emerging threat.

The United States is facing a deep and terrible crisis in Northeast Asia, and the repeated statements by the secretary of state and others to the contrary are making it worse. The president has said he would consider using force against North Korea, and he has deployed bombers to the area -- presumably to send a signal of strength and determination. But the North Koreans can read the newspapers as well as the president's speeches, and the signal they see there is very different. Of the 10 divisions in the active Army, eight are deployed or deploying to the Persian Gulf, Bosnia and Afghanistan. Of 12 aircraft carrier battle groups, five are deployed to the gulf region, three are undergoing maintenance and a fourth has just emerged from a maintenance period, leaving only three available for immediate action. There are literally no more forces with which we could meet a North Korean attack. At the same time, the president's bellicose talk may convince the North Koreans that time is running out for them. Can they afford to wait until we are done with Iraq and are free to concentrate our efforts and forces on them? This same combination of hostility, damaging policies and military weakness convinced the Japanese that the time had come to attack in December 1941. Interestingly, they had no expectation that they could defeat us in a war then. They hoped instead to force a change in our policies by attacking when we were distracted. What might the North Koreans try in a similar vein if they, too, become convinced that an attack or its plausible threat could lead to a negotiated settlement instead of all-out war?

There are a number of possible lessons to be drawn from this situation. One, commonly picked up by opponents of the war against Iraq, is that we should not fight that war now. This conclusion is clearly invalid. However unwise the course of action we have followed in the Iraq crisis to this point, the consequences of backing down now would be horrific.

Saddam Hussein would conclude that he can in fact protect himself by splitting international opinion without complying with any inspections regime. He would be emboldened to pursue weapons of mass destruction and surely to give terrorists access to them as well. Why shouldn't he, as we are already willing to attack him based on our fear that he might do so? What is more, our ability to deter other rogue states would be deeply compromised by the shattering of our international credibility. Abandoning the war against Iraq now would be a victory not for the "international community" but for aggressive, dictatorial rogue states.

Another lesson commonly drawn is that we should "engage" North Korea diplomatically. The problem with this is that since 1994 we have trained the North Korean government to become a blackmail regime. In every crisis, it starts by violating international agreements and agreements made directly with us, by threatening to develop weapons of mass destruction. It usually escalates by firing missiles, shadowing our aircraft or our allies' ships, or taking some other unfriendly action. Eventually, we come to the bargaining table and bribe Pyongyang to return to agreements it has already violated several times.

This kind of "engagement" is unacceptable. It will never lead to security in East Asia as long as the current regime is in power in Pyongyang, and it may even serve to keep that regime in power longer through the bribes that we pay. What is more, it is clear that the North Koreans probably already have a small number of nuclear weapons and can make many more fairly quickly. We will never be able to be confident that they do not have such weapons after this point, whatever they say or do -- and the addition of nuclear blackmail to the pattern is terrifying.

The clearest lesson of all is the one that is never discussed. We are in a period of grave national crisis, engaged in three major peacekeeping operations, preparing for one major war and having to contemplate another one that might begin at the same time (but in any event will not begin on our timetable). Our armed forces -- all of them -- are stretched beyond the danger point into crisis.

Nor will this problem disappear with the conclusion of a successful war in Iraq. Already it is being estimated that at least two divisions -- and possibly many more -- will be required to maintain peace in postwar Iraq and help establish a new government there. By the 3 to 1 logic of deployments (in which one unit is deployed, one is recovering from its deployment and one is preparing for deployment to an area), it would take six of our 10 divisions just to maintain two (the lowest estimate) in Iraq. Three more would be required to maintain one in Afghanistan (and we will not be able to reduce that requirement without sacrificing much of what we gained by defeating the Taliban in the first place). With only two divisions earmarked for Korea, that is more than the available force. Even the lowest estimate of what will be needed to keep the peace in Iraq is enough to break the back of the Army.

That the administration has not yet called for an increase in the size of the armed forces is the height of irresponsibility. It should do so immediately. Whether one supports our foreign policy or not, we have left our troops dangerously exposed, and that is unacceptable. We must make clear to the North Koreans -- and other potential aggressors -- that there will be no window of opportunity. The security of the United States and the future peace of the world now hang in the balance.

The writer is a military historian and co-author of "While America Sleeps."