As recently as December 1997, the Central Intelligence Agency assured Congress that it would be another 15 years before rogue nations like North Korea had ballistic missiles that could reach Alaska or Hawaii. Eight months later, that assumption went down in flames when the North Koreans fired their three-stage Taepo Dong 1 missile across Japan. The Department of Defense has since reversed its position and announced plans to develop a national missile defense system.

Once again, a threat has turned out to be closer and more serious than we had thought. It is also a reminder that our technological leadership is not guaranteed to be permanent. It can fade away if neglected.

After the Soviet Union fell and the Cold War ended, we entered a "strategic pause," during which no real challenge to the military superiority of the United States was foreseen. It was supposed to be a time when we could cut forces, ease the operational pressures on those forces, and then make orderly investments and prepare for the future.

The force cuts happened--but none of the rest of it did. As a result, the defense program today is pulled in three different and competing directions.

• One pull is by current operations, especially the "engagement and enlargement" operations so favored by the Clinton Administration. When the sweeping cuts were made, no one anticipated that the employment rate for the armed forces was about to pick up by 400 percent. Expectations about the scope and duration of these operations have often been optimistic. US troops were supposed to be out of Bosnia by December 1996, at the latest.

Within the defense program, greater importance is now accorded to smaller-scale contingencies and military operations other than war. The armed forces have adjusted accordingly. For example, the Air Force has concluded that peacetime deployments will be a continuing way of life and is reorganizing itself into 10 aerospace expeditionary forces.

• A second pull on defense resources is maintaining a force that can respond to two overlapping major theater wars. This requirement is sometimes disparaged by people who do not know any better, but a lesser standard for sizing the force is not feasible.

The two conflict standard was adopted in 1993 when the Bottom-Up Review went searching for a rationale to justify a budget reduction that had already been decided upon. This approach was selected after a lower-cost concept called "Win-Hold-Win" failed to establish credibility on any front, including Congress.

The need to cover one theater conflict is indisputable. In addition, however, there must be enough forces to form a reasonable reserve, to serve as a hedge and deterrent against simultaneous trouble elsewhere, and to perform other military missions. The minimum standard for sizing the force is more than one regional conflict, and if it isn't two conflicts, it's very close.

• The third pull is what the National Defense Panel report called "transformation" of the force. There are varying interpretations of what that entails, but it includes taking advantage of the technological revolution in military affairs, exploiting the possibilities of space, and preparing to meet new threats that range from the proliferation of weapons of mass destruction to the vulnerability of our national infrastructures.

One of the changes brought by the revolution in military affairs was that information and long-range precision strike technology offered an alternative to traditional models of warfare built around massed forces, high casualties, and battle lines drawn on the ground.

Of the competing demands on defense resources, the priority has been tipped in favor of current operations, many of which are loosely defined and open-ended. These operations have tended to draw the services into costly, manpower-intensive activities and toward capabilities that may differ from those needed to fight and win regional wars.

The additional money proposed in this year's defense budget is not even enough to solve the shortfall in readiness and current operations. It does not begin to address the needs of the future. In fact, air and space systems--the linchpins of the revolution in military affairs--are frequently under attack as unaffordable and unnecessary.

The armed forces have obviously made gains, some of them spectacular. For example, although the Air Force bomber fleet of 2004 will be about half the size of the 1992 fleet, it will be able to hold 10 times as many targets at risk.

But in a broader sense, we have failed to exploit the strategic pause. The emphasis has been on short term considerations, and expanded peacetime operations have consumed a big share of defense resources. In their present circumstances, the armed forces are prepared to meet the two-conflict standard only with a stipulation of "moderate to high" risk.

The rest of the world is not standing still. The North Korean ballistic missiles are just one example of the spread of advanced military technology. Our own force modernization programs are underfunded and strung out. We have not made much progress at all toward transformation.

The strategic-pause window as initially projected expires around 2010--or perhaps 2015 if we're lucky. We have essentially missed our chance in the first part of the window, and we are well along toward letting the opportunity that remains slip away.