Now we have to hope the Iraqis can hold things together.

The key fact about President Barack Obama's decision to end the war in Iraq—pulling out all U.S. combat brigades by August 2010 and all U.S. forces, period, by the end of 2011—is that he had little choice about the matter.

For some time now, the United States has had less and less say over the nature and direction of post-Saddam Iraq. We declared it to be a sovereign nation, at which point its leaders started acting as if it were true.

Last November, the two governments signed a Status of Forces Agreement, the standard contract by which one nation allows another to keep troops within its borders. But this accord has a special clause, Article 24, which states, in part, "All U.S. forces are to withdraw from all Iraqi territory, waters, and airspace no later than the 31^st of December of 2011." No ifs, ands, or buts.

That article further states: "All U.S. combat forces are to withdraw from Iraqi cities, villages, and towns … no later than 30 June 2009."

The treaty doesn't define "combat forces," so there's some wiggle room here. President Obama appears to interpret the phrase to mean combat brigades. In his speech today at Camp Lejeune, N.C., he said that all combat brigades would be withdrawn by August 2010. Still, it's not out of the question that U.S. combat troops (and, by the way, just what are "noncombat troops"?) might continue to patrol in smaller configurations than brigades even after that deadline has passed. The Iraqis' intent is clear: They want us assuming a much lower profile by this summer, a year before the deadline that even Obama has set.

As for the Democratic lawmakers and anti-war activists who criticize the president for wanting to keep 35,000 to 50,000 troops in Iraq even after that August 2010 deadline, he made it clear in his speech that those troops are strictly transitional; they'll all be gone by the end of 2011—and would be, even if he preferred otherwise—because the SOFA requires them to be gone.

Before President Obama announced his timetable, there were debates within the administration over how rapidly the pullout should flow. During the election campaign, Obama had said he'd withdraw all combat troops within 16 months of taking office. Since then, some military officers have argued for stretching this schedule to 23 months. The president's final timetable, which amounts to 19 months (measured from Inauguration Day), appears to be a difference-splitter.

In a teleconference with reporters after the speech, Secretary of Defense Robert Gates explained that Gen. Raymond Odierno, commander of U.S. forces in Iraq, had advocated keeping combat troops for a long enough time to provide security during, and a little after, Iraq's upcoming elections; Obama's original 16-month plan, he argued, wouldn't cover the full span. The president compromised.