Is a vital US interest at stake? Will we commit sufficient resources to win? Will we sustain the commitment? Are the objectives clearly defined? Is there reasonable expectation that the public and Congress will support the operation? Have we exhausted our other options?

Unlike our failed adventure in Vietnam, the Gulf War of 1991 met all of the Weinberger criteria. The nation had learned its lesson--or so it seemed at the time--and had found a wiser standard for when and how our armed forces go to war.

However, Les Aspin, the first Secretary of Defense in the Clinton Administration, rejected what he called the "All or Nothing" school of strategy and sought a less restrictive rule for committing troops to combat. He endorsed a "Limited Objectives" approach in which, for example, the purpose of air strikes might be to send political signals to an adversary.

A year later, Aspin was gone from the Pentagon, in part because 18 American soldiers died when an insufficiently supported and supposedly limited humanitarian relief mission in Somalia suddenly turned into a lethal firefight, but the "Limited Objectives" concept rolled on.

Since then, the United States has progressively lowered the threshold for engaging in combat. We have become increasingly willing to employ the armed forces in situations where the military purposes are vague or undefined.

For the past eight years, we have maintained a military force in the vicinity of the Persian Gulf to "contain" Saddam Hussein's regime in Iraq. We have conducted several symbolic strikes against Iraq. These were not meant to have any real military effect, but rather to send messages. There have also been countless threats and warnings. Somewhere along the way, the coalition that stood with the United States in the Gulf War atrophied.

Last fall, in a prelude to the latest crisis, we responded to violation of the no-fly zone by bringing in an aircraft carrier from the South China Sea, 7,000 miles away, "to send a signal to Iraq." A clearer signal, perhaps, was sent by our presumption that we could not call upon--or even mention in the Administration's blustery warnings--the 120 Air Force combat aircraft already there.

A month later, Saddam threw out the Americans on the UN inspection teams looking for his hidden chemical and biological weapons. When he grew bolder in his defiance, declaring various sites off limits to inspectors, the United States responded with-what else?--more warnings.

We built up a large theater force, including hundreds of aircraft, dozens of ships, and 33,000 troops. It was not clear, though, what we actually intended to do if Saddam did not take the messages we were sending him to heart.

Our objective was also unclear. In January, it was to "deny" Saddam the ability to build and use weapons of mass destruction. A month later, it was to "substantially reduce or delay" his acquisition of such weapons.

As the prospect of a shooting war drew closer, it was obvious that we were improvising. We had put our faith in sending signals and when that failed, we were caught short in our planning.

The Administration finally understood that "pinprick" attacks would be useless. Airpower was our best asset, but we could not find and destroy Saddam's entire chemical weapons capability with air strikes. The connection was tenuous, at best, between the force we threatened to unleash and the results we expected to achieve by doing so.

To make matters worse, our determination was lukewarm. Secretary of State Madeleine Albright explained that "toppling Saddam requires a far vaster commitment of military force and a far greater risk" than we were prepared to undertake.

We eventually settled for Saddam's promise to let the inspectors back in, in return for which he received all sorts of valuable concessions. No wonder he declared Feb. 23 the "Day of the Flag" to mark Iraq's victory over the United States.

For all of the things that were wrong with his mission to Baghdad, UN Secretary General Kofi Annan got us off a difficult hook. We were not in a position to follow through on what had been said in all of our signals, messages, and warnings. The nation gained another chance to learn about the exercise of power.

The Administration could benefit from study of the Weinberger Doctrine, which holds up quite well against the backdrop of recent events. The use of military force to send signals to an adversary fits comfortably within it--provided we are ready to take serious, relevant, and sustained action if our warning shot fails.

Strategy must be based on objectives that can be specified and which we have the means and the will to accomplish. It will not work if we do not know what our objectives are or if we are short on either capability or will.

Improvisation and warnings that we are not fully determined to back up are not a substitute for strategy. They are an invitation to disaster.