In November 2008, representatives of U.S. President George W. Bush and Iraqi Prime Minister Nouri al-Maliki signed a Status of Forces Agreement (SOFA), which established the operational and legal framework for U.S. soldiers and their civilian counterparts in Iraq. The key line in the agreement was contained in Article 24: “All the United States Forces shall withdraw from all Iraqi territory no later than December 31, 2011.” In a major speech a few months later, newly inaugurated U.S. President Barack Obama affirmed that he intended to uphold the deadline.

But it is proving difficult for the U.S. military to say goodbye to Iraq, after what has now amounted to a 21-year engagement, including nearly 4,000 days of no-fly zones and 3,000 days of stability operations since the first Gulf War. U.S. defense officials have recently begun begging and bluffing to compel Iraq’s government to ask the United States to stay. In April, Admiral Michael Mullen, chairman of the Joint Chiefs of Staff, gave Maliki an ultimatum: “Should the Iraqi government desire to discuss the potential for some U.S. troops to stay,” he warned, “it needs to start soon -- very soon -- should there be any chance of avoiding irrevocable logistics and operational decisions we must make in the coming weeks.”

Yet Baghdad seems unable to make up its mind. Some political leaders privately lobby for U.S. troops to stay, but only in training and advising roles. Still, most Iraqis and many members the Iraqi parliament are weary of a continued American military presence, which is problematic since U.S. officials insist that an updated SOFA be approved by the parliament. Iraqi President Jalal Talabani had requested that Baghdad’s fractious political blocs decide by last Saturday whether to ask for an extension of U.S. troop presence into next year. They were unable to reach a consensus and have postponed additional negotiations on the topic “until further notice.”

Still, according to anonymous U.S. officials, the White House is prepared to keep 10,000 ground troops in Iraq after the end of this year. It apparently has two reasons. The first is to prevent Iran from supplying improvised explosive devices and rockets to Shia militants in Iraq who have used such weapons to kill U.S. troops. According to U.S. officials, nine of the 15 U.S. soldiers who were killed in Iraq in June died from such attacks. The second is that somehow the mere presence of 10,000 U.S. troops will mitigate Iran’s long-term influence in Iraq, which has been a proxy battlefield between Washington and Tehran for decades.

There are a few problems with this logic. For starters, it does not make sense for the United States to keep soldiers in Iraq to prevent Iranians from providing Iraqi Shias with weapons to kill U.S. soldiers in Iraq. As the Pentagon noted in its “Measuring Security and Stability in Iraq” report last summer, “Iran will likely continue providing Shi’a proxy groups in Iraq with funding and lethal aid, calibrating support based on several factors, including Iran’s assessment of U.S. Force posture during redeployment.” In other words, Iran will continue its behavior as long as there are U.S. soldiers in Iraq to target, which suggests that the surest and fastest way to prevent further bloodshed is to withdraw the remaining U.S. soldiers on schedule.

Further, no matter what the United States does, Iran will continue to try to influence Iraq. Tehran has a strategic interest in its neighbor’s political makeup and will use a combination of soft-power initiatives -- including outreach to sympathetic political parties, such as Dawa, Maliki’s Islamic party -- and providing weapons to Shia extremist groups for targeting U.S. forces and gaining the upper hand in the region. Countering those attempts should not primarily be the job of a diminished and constrained U.S. military presence; diplomats are better suited for such a mission, and the transition to a U.S. civilian-led mission in Iraq is already under way. After 2011, the U.S. civilian presence in Iraq will remain massive. The State Department will eventually deploy some 17,000 personnel at 15 sites across the country, 5,100 of whom will be security contractors.

If the 46,000 U.S. troops in Iraq now (and the 166,000 U.S. troops deployed there during the 2007 surge) have not been able to shut down the Iranian weapons pipeline, there is no reason to believe that the 10,000 troops the Obama administration would have stay in the country could do so. And even if Iran’s weapons continued to flow into Iraq after 2011, the U.S. military would have few appealing options for addressing the problem along the 900-mile Iran-Iraq border.

The United States could choose to target assets and operatives outside of Iraq that are connected with Iran’s Revolutionary Guard. But that would not be wise, either. In 2008, U.S. special operations forces did something similar when they killed Abu Ghadiya, an al Qaeda commander, in Sukkariyah, a city near Syria’s border with Iraq. The mission did nothing to convince the Syrian government to close its borders to al Qaeda, which U.S. officials claimed Syria had been directly supporting. Such a move against Iran would be perceived as an attack on the state, and any resulting retaliation would needlessly place Americans in Iraq in immediate danger.

If the Obama administration believes that leaving troops in Iraq would prevent the impression that Iran is “driving us out,” as a senior U.S. defense official put it, it should reconsider. The United States should not indefinitely maintain 10,000 troops in Iraq for second-order psychological reasons, such as attempting to alter the thinking of Tehran’s opaque political leadership structure. Furthermore, U.S. strategy in Iraq should not be based on what Tehran might say about it.

Instead, the United States ought to base its Iraq strategy on a clear-eyed assessment of national interests, which would mean ending the U.S. military presence, reducing the operation’s financial burden on U.S. taxpayers, and providing assistance to Iraq so that it can defend its borders. Sooner or later (and probably sooner) Iraq must be able to protect its own sovereign territory. Whether it succeeds is not a matter of resources; as U.S. Secretary of Defense Leon Panetta recently noted, the “damn country has a hell of a lot of resources.” It is primarily a matter of Baghdad’s political will, which was lacking when 166,000 U.S. troops were fighting the Sunni-led insurgency at a cost of some $12 billion a month in 2007, and remains lacking today.

In the meantime, the United States should continue to help build up Iraq’s military capacity. As in other countries, this effort should be led by the State Department in Washington and the U.S. embassy’s Office of Security Cooperation in Baghdad. Efforts should include training Iraqi Ministry of Interior police and border forces, educating Iraqi officers at U.S. war colleges and academies, conducting military-military exchanges, and sharing intelligence. The United States could also help by selling Iraq advanced conventional weaponry; Iraq is reportedly interested in buying 36 F-16 fighter jets from Lockheed Martin.

If the Obama administration does convince Maliki to ask U.S. troops to stay, it must explain what the operational constraints of a new SOFA would be, and provide a new timetable for withdrawal. Moreover, in a war that two-thirds of U.S. citizens oppose and that has left 4,474 U.S. soldiers dead, Obama should be pressed to provide a clear and compelling reason why leaving 10,000 troops in Iraq is in the United States’ national interest and, more specifically, how it would plausibly mitigate Iranian influence. Despite his mastery of rhetoric and eloquence, chances are that he will not be able to, which is why the United States should implement the 2008 SOFA now and finally end its military presence in Iraq.