The current discussion about drawing down American troops in Iraq -- whether "immediately," "rapidly" or "as soon as possible" -- would be amusing were it not so dangerously divorced from reality. There could be no greater mistake than drawing down the U.S. force now, at a moment when there is real hope for success if the United States perseveres.

But Democrats calling for these reductions are not the only ones to blame for giving the impression, however mistaken, that the United States is growing short of breath in Iraq just as the situation appears to be improving. The Bush administration has been talking about reducing forces in Iraq ever since the invasion ended in 2003. Indeed, the history of the administration's endless promises to reduce the size of the force in Iraq puts the current discussion in perspective.

On May 3, 2003, the New York Times reported administration plans to "withdraw most United States combat forces from Iraq over the next several months," reducing the number of troops from 130,000 to 30,000 by the fall of 2003. According to officials, the administration did "not want substantial numbers of American forces to be tied down in Iraq" and was "eager to avoid the specter of American occupation."

That didn't quite pan out. After the invasion, the U.S. force in Iraq turned out to be too small to bring order to the country. The calculation of Pentagon officials such as Paul Wolfowitz, who claimed that the force necessary to bring peace and stability to Iraq need not be larger than the force necessary to invade it, proved mistaken. And so, a year after the invasion, 135,000 troops still were in Iraq, too many to avoid "the specter of American occupation" but too few to make that occupation effective in bringing order and preventing the rise of an armed opposition.

Nevertheless, the Bush administration continued looking for reductions. Pentagon officials told Congress that the numbers would begin to decline significantly by the summer of 2004. But as summer approached, they began asking for more money to maintain troop levels, and some 20,000 troops scheduled for return home had to be kept in the field. In early 2004 administration officials again talked about drawing down forces significantly, perhaps in time for the November elections. That turned out to be wrong, too. By December 2004 troop strength was at 150,000.

Last April, when 142,000 American troops were in Iraq, senior military officials were talking about possibly reducing the force to a little over 100,000 by early 2006. But by August, according to The Post, Pentagon plans called for an increase of 10,000 troops in the fall, with a possible decrease to around 120,000 by the spring of 2006 and further reductions by the end of 2006 to around 100,000. Last month about 150,000 troops were deployed, and, according to the Pentagon, the "current thinking" was that the number could fall to 138,000 after the coming Iraqi elections and then to below 100,000 by late 2006.

President Bush himself repeatedly insisted that he had no intention of withdrawing from Iraq or even reducing the force short of victory. But apparently the president has little control over what his own officials say and do. So there has been a steady drumbeat of anticipated reductions ever since the spring of 2003, with each promise and plan inevitably broken or undone by persistent military realities in Iraq.

Is it any wonder that Democrats uncomfortable defending the war they once supported now feel comfortable talking about withdrawal? Their arguments come directly from administration talking points. Some top military and Pentagon officials have, from the beginning, asserted that the presence of large numbers of U.S. troops is a big reason for the rise of the insurgency and that a "small footprint" was the key ingredient to success. This has proved erroneous. But how much should we blame Nancy Pelosi, John Murtha and John Kerry for making the very same argument and suggesting that Iraq can be made stable and secure only by a steady reduction of forces? Has any senior military officer or top Pentagon official really explained why this is not the case?

They had better begin doing so, even though it might mean owning up to their miscalculation at the end of the war in 2003. The U.S. force was too small at the beginning and remained too small for most of the past two years. As a result, it did not play the role that an occupying force must play in bringing stability to the country, the prerequisites to producing a secure Iraq capable of standing on its own feet. Instead of worrying about an overly large American "footprint," administration and military officials should have been worrying about stopping armed opposition from spreading and about the moral and practical responsibility of providing security to the people whose country we had invaded.

Now that indigenous Iraqi forces are starting to fight more effectively and in greater numbers, we may be getting to the point where the current U.S. force of more than 150,000 troops is adequate to start providing Iraqis the necessary security and stability. We may be today where we should have been two years ago. If American force levels hold steady while Iraqi force levels increase, that gradually shifts the balance in the conflict in our favor. But we will almost certainly have to maintain something like these levels for another two years, and possibly longer.

Talk of reductions and withdrawal is as unhelpful as it almost certainly is ephemeral. For 2 1/2 years, despite the endless promise of reductions, despite election battles, scandals and shifting political fortunes, the United States has maintained a steady force of 130,000 to 150,000 troops in Iraq. You can bet that the numbers will not be dramatically smaller a year from now or even two years from now. Wouldn't we be better off, wouldn't our prospects for success be greater, if we just admitted it? Better still, the administration could explain why it is so important to keep these troops in place so that the public understands the long road ahead. It could start taking steps to increase the overall size of the U.S. military so that the sustained deployment doesn't "break" the Army. And it could stop making false promises of reductions that cannot and should not occur until Iraq is indeed secure and stable.

Robert Kagan, a senior associate at the Carnegie Endowment for International Peace and transatlantic fellow at the German Marshall Fund, writes a monthly column for The Post.