President Barack Obama's plan to draw down U.S. forces below fifty thousand troops by August 2010-and to get to zero by the end of 2011-confirms he will not make Baghdad another U.S. outpost. This will not be another Japan or South Korea.

Many of the leading advocates of the war in Iraq can't be pleased. They saw post-Saddam Iraq as a crucial base for U.S. military power. Writing in the Weekly Standard in May 2003, Tom Donnelly of the American Enterprise Institute maintained that U.S. interests at stake in Iraq had increased following Saddam Hussein's ouster. Donnelly called for a "quasi-permanent American garrison in Iraq" to protect these interests. When Defense Secretary Donald Rumsfeld asserted that the Pentagon was not planning to keep permanent bases in Iraq, Max Boot of the Council on Foreign Relations exclaimed, "If they're not, they should be." Indeed, Boot implored USA Today readers to "get used to U.S. troops being deployed [in Iraq] for years, possibly decades, to come."

It could be argued that such a sufficient space of time has elapsed that America's interests in the region are secure. It seems more likely that the expectations that Iraqis would welcome a permanent U.S. military presence in their country were unrealistic at the outset.

They grew even more unrealistic as Americans turned decisively against the war. Those people who believed that Obama would quickly end the war might be disappointed that the bulk of troop withdrawals will not begin for nearly a year, and that there will be a very sizable U.S. military presence for nearly three years-but they shouldn't be surprised. Obama always qualified his call for ending the Iraq War by stipulating that he would leave behind a residual force. Now we know how large that residual force will be, and how long it will remain.

In truth, however, we've known the end date for several months. The status of forces agreement (SOFA) concluded by the Maliki government and the outgoing Bush administration stipulated that all U.S. military personnel would leave Iraq by a date certain. Obama and his national-security team are merely adhering to that deadline.

The United States and Iraq could negotiate a new SOFA, but that seems highly unlikely. Responding to a question from David Gregory on NBC's Meet the Press, Secretary of Defense Robert Gates stressed that changes to the SOFA would not constitute a renegotiation, but rather "a completely new negotiation" on an entirely new agreement, a scenario that he dismissed as "completely hypothetical." And when Gregory pointed to earlier suggestions that U.S. forces might need to remain in Iraq "at least until 2015," Gates explained that he had made such remarks "before the SOFA was signed . . . And before we made a commitment to be out of there by 2011."

Implausible predictions about the benefits that would flow from the Iraq War, including the belief that Washington would be able to use Iraq as a staging ground for future operations in the region, helped to mobilize public support for the venture in late 2002, but that support proved short-lived. Senator John McCain's inability or unwillingness to appreciate the depths of public opposition-including his refusal to contemplate anything other than an open-ended mission-helped to ensure his defeat last November.

Democrats in Congress were unable to force an end to the war, but Americans have Iraqi lawmakers to thank for setting the parameters for the Obama plan. If Obama keeps to his stated course, and if Iraqis hold us to the promises that we have made, Americans can be confident that the war will come to an end-just not nearly as quickly as the vast majority of us had wished.

Christopher Preble is director of foreign policy studies at the Cato Institute and the author of The Power Problem: How American Military Dominance Makes Us Less Safe, Less Prosperous, and Less Free (Cornell University Press, April 2009).