THE WAR IN AFGHANISTAN is a long way from over. Despite the premature self-congratulation that was common until recent weeks, we haven’t won it yet, and our victory or defeat will rest largely on decisions our leaders are making now. From the beginning of the conflict, the administration has been determined to minimize the use of ground forces. Administration supporters insisted that airpower alone could take down the Taliban and destroy al Qaeda. But the call for ground troops was always based on the expectation that the fall of the Taliban would create a delicate situation in which we would not be in control. That is precisely what has happened. In the months since the collapse of the Taliban, American and Western forces have largely confined themselves to Kandahar, Kabul, and Bagram airbase and to search-and-destroy missions in the mountains along the Pakistani border. They have established no meaningful presence in other major cities, leaving whole regions of the country in anarchy. The result has been a return to warlordism. Powerful former mujahedeen commanders are setting up their own palatinates and armies, and every day that these developments go unopposed makes the peaceful reunification of the country more difficult. That is why both Afghan leaders and international observers are calling with increasing shrillness for the deployment of tens of thousands of international peacekeepers. The refusal of the administration to consider such a step is ill-advised. The reason we attacked Afghanistan in the first place was that anarchy, civil war, and Islamic radicalism had created an environment conducive to terrorist planning and training, aimed at attacking the United States and acquiring weapons of mass destruction. The only way to ensure the same thing doesn’t happen again is to establish a government in Kabul that can control the country. This cannot be done from the air, and it cannot be done in six months. It requires the long-term deployment of significant American and Western ground forces. Had we sent such forces into the country during or immediately after the air campaign, we would now control the major cities and regions. Instead, we confront the challenge of establishing first international, then Afghan, control of the country in the face of entrenched warlords. As we attempt this, we are likely to suffer low-level, small-scale, but constant guerrilla attacks on convoys and strongpoints. This sort of warfare offers few obvious successes, but it cannot be avoided. The current regime in Kabul cannot quickly build its own armed forces and police. Were it to enlist some of the armed forces already in the country that belong to warlords and partisan groups, it would probably trigger civil war. Yet order is needed during the several years it will take to develop adequate police and armed forces, not to mention a functioning government and civil institutions, for Afghanistan. A force must be introduced that can police the country in the short and medium term, hunt down al Qaeda and Taliban remnants, and deter and if necessary defeat warlords who oppose our efforts to bend them to the will of a government they do not respect. We will need to send in around 20,000 ground forces, perhaps more, including a mix of heavy and light units. They will have to secure the major cities (Herat, Shindand, Mazar-i-Sharif, etc.) and the lines of communication between them. Although light heliborne troops are ideal for search-and-destroy missions in Afghanistan, heavy forces are best for holding key population centers and patrolling roads. This deployment will also require a substantial increase in our “logistical footprint” in the country and the region, and it will tax our support services heavily. The logistical difficulties, however, must not deter us from accomplishing tasks critical to our success. This mission, though difficult, is not impossible. Right now, our armed forces still hold the respect of most Afghans, including the warlords. They fear our bombers and the ground forces that can call in and adjust bomb strikes. If we make it clear that we are there to stay, that the bombers will continue to patrol the skies, and that it is a bad idea to annoy Americans whose radios can communicate with those bombers, there is a considerable prospect for our success. Unfortunately, the administration has sent the opposite signal. We are getting out in a matter of months, its spokesmen have repeatedly said. We will not increase our forces. We will not oppose the warlords. Those statements account in part for the current apparent peace: The Taliban, al Qaeda, and the warlords are waiting us out. Each believes it can prevail when we are gone. And there is another danger: that of gradual escalation. Situations will arise presenting us with the choice to pull out or stay in. The likelihood of collapse upon our withdrawal will prompt us to stay, yet with forces woefully inadequate to pacifying the country. As soon as it becomes clear to our opponents that we are staying longer than planned, some of them will decide to attack their enemies or us and our allies. At that point, to avoid a clear defeat, we will probably escalate–although as slowly as possible since the administration does not want us there at all. Instead, we should choose another policy. It requires facing up to the reality that we are in Afghanistan. We went there to destroy an intolerable threat to our security. Unless we win, the threat will return. We should deploy the ground troops that are needed to secure stability while a new government is chosen and consolidates its hold. Any other course of action now could lead to our ultimate defeat. Frederick Kagan is a military historian and the co-author of “While America Sleeps.”