The widespread desire to get out of Iraq is producing much wishful thinking about how such a withdrawal can be accomplished and at what cost. The common theme of most proposals--including those rumored to be dominating the thinking of the Baker-Hamilton Commission--is that the only solution in Iraq is political, and perhaps also diplomatic, rather than military. The common flaw in each of these proposals is that no political solution can be achieved without a measure of military success by the combined forces of the U.S. and Iraqi armies.

The problem in Iraq, until now, has not been the administration's failure to recognize the necessity of a political solution. Nor is it that the administration has set its sights in Iraq too high. For quite some time now, officials throughout the government, including the White House, would have been delighted to accept an outcome other than a perfectly unified Iraq if it could plausibly allow the country to sustain itself even for a year without descending into bloody civil war. As for the question of democracy, the administration's efforts to support democratic government in Iraq have been more pragmatic than idealistic. The alternative to democratic government in Iraq is some form of authoritarian rule. But where is the strongman who can take control of Iraq? Would he be Sunni or Shia? Placing either sectarian group in charge would only set off civil war. As a practical matter, not as an idealistic matter, no government can succeed in Iraq that is not based on a bargain between the different sectarian groups, and no bargain will be sustainable that does not in some way reflect the people's desires.

No such bargain can even be reached, however, without a minimum level of order and security in Iraq. Unless the majority of Iraqi people can be protected from terrorist bombers, insurgents, and death squads, they will not be able to negotiate and sustain any political settlement. When the U.S. and Iraqi forces fail to guarantee their security, they naturally look to their own sectarian forces for protection.

The expectation that a U.S. withdrawal or "phased redeployment" will force Iraqis to reach some kind of accommodation with one another has been disproved by three years of painful experience. American officials have been promising to begin drawing down U.S. forces in Iraq since the beginning of the occupation. Roughly every six months, Pentagon officials have announced their intention to cut the force levels in half within a year. Each of these drawdowns was supposed to follow various milestones of political success--an election or the establishment of a new government. But each anticipated political breakthrough has been undermined by new spikes in insurgent attacks. The problem has not been a lack of political progress, really, but a lack of military progress to sustain political advances.

It is precisely the illusion that a political solution is possible in the midst of rampant violence that has gotten us where we are today. What's needed in Iraq are not more clever plans but more U.S. troops to provide the security to make any plan workable. Even those seeking a way out of Iraq as soon as possible should understand the need for an immediate surge in U.S. troop levels to provide the stability necessary so that eventual withdrawal will not produce chaos and an implosion of the Iraqi state.

The first priority ought to be to secure Baghdad, which U.S. policy has disastrously failed to do. To accomplish this, the United States should send an additional 50,000 troops at least, the bulk of them to Baghdad so that the city can be made safe for its inhabitants, but without drawing forces from elsewhere in the country. Once Baghdad is secure, U.S. and Iraqi forces could extend their operations into Sunni-controlled areas. This will take time. But a secure Baghdad would provide at least one pillar on which any eventual political settlement could be based.

Some claim that we don't have 50,000 troops to send to Iraq. In fact, the troops are available. Sending additional forces to Iraq means lengthening troop rotations, as the United States has done in previous major conflicts. Sustaining such an increased deployment, however, will require a substantial increase in the overall size of the Army and Marines. This increase, which does not require a draft but does require money, is necessary regardless of what we do in Iraq. It is stunning that this administration has attempted to fight two wars and has envisioned other possible interventions with a force clearly inadequate for these global commitments.

We should not kid ourselves about the cost of failing to create a relatively secure situation in Iraq. The sectarian violence we are seeing today will seem minor compared with the massive bloodshed of a genuine Iraqi civil war. The idea of a "phased redeployment" implies a smooth, gradual process whereby U.S. military forces withdraw and Iraqis peacefully adjust. It's almost impossible to imagine events unfolding that way. Once we begin the process of U.S. withdrawal, there will be an eruption of violence to fill the vacuum. International terrorist groups will find themselves unchallenged in parts of Iraq and able to establish new bases from which to launch attacks against the United States and its allies. It is fanciful to imagine that the Iraqis themselves will take action against these groups: They will have their hands full fighting one another.

Under these circumstances, any "redeployment" of U.S. forces "over the horizon" would be short-lived. Withdrawal is, in this sense, an illusion. Many who favor withdrawal assume we will be able to tolerate whatever follows in the wake of our departure. This is a bad prediction of American behavior. The chances that President Bush--or a President McCain, President Clinton, or President Obama--will be able to stand by and allow Iraq to become the next Afghanistan are small. It would be far better to improve the situation in Iraq now, while we still have a chance. The alternative is to withdraw, allow Iraq to implode--and find ourselves, one or two years down the road, having to fight our way back in. 

Robert Kagan is a contributing editor at The New Republic and the author of Dangerous Nation: America's Place in the World from its Earliest Days to the Dawn of the Twentieth Century.