As part of the SOFA, the United States is required to withdraw its military forces from Iraqi cities by June 30, 2009, and from the country entirely by the end of 2011. Though some critics think this timeline is too fast, there is a good chance that the U.S. may be forced to withdraw even sooner: In order to coax reticent parliamentarians into approving the agreement, the Maliki government has agreed to hold a national referendum in July of this year to ratify the SOFA. If the SOFA fails to pass, the United States would have just one year to withdraw all its military forces from Iraq.

Beyond forcing an expedited withdrawal, a failed referendum would likely cause even U.S. allies among Iraqi politicians to ratchet up the level of nationalist demagoguery against the U.S. military presence to position themselves for their parliamentary campaigns. In such a heated atmosphere, insurgents could also prove more likely to step up their activity against withdrawing U.S. troops, radicalizing the environment for parliamentary elections and further complicating the redeployment of U.S. troops. Whether or not a future U.S.-Iraqi military relationship is advisable beyond the terms of the SOFA, such a scenario would likely preclude the Iraqi government from seeking support for it. Opponents of the United States would also frame a withdrawal under these circumstances as a repudiation of the United States and a defeat for U.S. policy in the region.

In this context, significant drawdowns in upcoming months will become a litmus test for the credibility and seriousness of the Obama administration in respecting public commitments to withdraw U.S. forces from Iraq. While the exact timeline for withdrawing U.S. forces is less important, if no significant redeployments occur prior to the national referendum, Iraqi public opinion could very well conclude that Washington is determined to maintain a significant military presence in Iraq regardless of the public pronouncements and treaty obligations to the contrary.

Better that the U.S. begin withdrawal now, on its own terms--and in the process, enhance the chances that the SOFA will not be rejected by the Iraqi people. At the same time, President Obama would project an unmistakable message to the Arab world that the United States is serious in recalibrating the nature of its engagement with the region.

In some quarters, it is widely assumed that Iraqis' rhetorical opposition to the U.S. military presence belies a begrudging acceptance of U.S. troops as the price of preserving recent security gains. However, gambling on Iraqi support for a continuing foreign military presence would seem to be a risky policy-planning approach that could create the conditions for a hasty withdrawal on highly unfavorable terms.

Undoubtedly, U.S. forces continue to play a vital role in providing combat and logistical support to Iraqi forces. Their presence might also serve as a buffer against the outbreak of widespread ethno-sectarian warfare and provide a point of leverage--albeit of diminishing value--in prodding Iraqi political forces to come to terms with the fundamental questions on governance, territory, and resources that still divide the country. But even if advocates of a rapid redeployment of U.S. forces overestimate the capabilities of Iraqi forces to secure the country with diminished U.S. assistance, the continued presence of U.S. forces in any capacity is now wholly dependent on Iraqi approval of the SOFA. Iraqi public opinion now matters, whether we like it or not, and behaving as if the question of troop redeployments is a question to be answered solely in Washington will further strain U.S. relations with Iraq and the Arab world.

Michael Wahid Hanna is a program officer at The Century Foundation. This was originally published in The New Republic.