Announcing the results of his administration's first policy review on Afghanistan more than eight months ago, President Barack Obama declared, "I want the American people to understand that we have a clear and focused goal: to disrupt, dismantle and defeat al-Qaida in Pakistan and Afghanistan, and to prevent their return to either country in the future." To achieve those goals, the president explained, "we need a stronger, smarter and comprehensive strategy." Unfortunately, the strategy Obama announced tonight will not achieve it.

On Aug. 30, 2009 Gen. Stanley McChrystal, the top U.S. commander in Afghanistan, issued a report advocating, among other items, a surge of 40,000 troops into Afghanistan. Over subsequent months, this number became a political football. Both Vice President Joseph Biden and Gen. Karl Eikenberry, the U.S. ambassador in Kabul, advocated fewer troops. After lengthy deliberation, Obama on Tuesday night agreed to send 30,000 additional troops to Afghanistan, bringing the total U.S. commitment to over 100,000 troops. NATO, the administration hopes, will contribute enough to address the shortfall in McChrystal's request.

McChrystal is a veteran counterinsurgency expert. He made his request based not on politics, but a calculation of what it would take to win in Afghanistan. Obama has however refused to separate politics from national security. The problem is not troop numbers. When he declared on Tuesday, "These additional American and international troops will allow us to accelerate handing over responsibility to Afghan forces, and allow us to begin the transfer of our forces out of Afghanistan in July of 2011," the president has undercut the McChrystal plan and made success difficult to achieve.

There should be nothing wrong with an open-ended commitment to victory. In late 2006 and early 2007, when the Bush administration put the finishing touches on the strategy that would become the Iraq surge, Obama and many of his top aides questioned its wisdom. On July 19, 2007, for example, Obama declared, "Here's what we know. The surge has not worked." That a year later Obama scrubbed his criticism from his campaign website suggests that today he recognizes the positive impact of George W. Bush's decision. What Obama fails to understand, however, is that the surge is not only a military strategy, but a psychological one as well.

Iraq's surge succeeded because Bush convinced Iraqis that he would not subvert his commitment to victory to politics. Bush's actions showed insurgents had misjudged the U.S. and that Bin Laden was wrong: The U.S. was no paper tiger. Iraqis, no more attracted to al-Qaida's extreme vision than ordinary Afghans are to the Taliban, believed America to be strong. Rather than make accommodations to the terrorists, Iraqis could fight them. The Sunni tribesmen believed that the U.S. would guard their back, and let neither al-Qaida nor Iranian proxies run roughshod over them. For Iraqis and Afghans, it is an easy decision to ally with militarily superior forces led by a commander-in-chief with a clear and demonstrable will to victory.

Obama is not Bush. By declaring his commitment finite, he removes the psychological force from his surge. NATO allies, who, because of limits they place on their troops' activities, are hardly dependable on the best days, will understand that absent U.S. commitment, furthering their own commitments is silly. Pakistan will bolster its support for the Taliban. In Islamabad's calculation, militant Islam is a lesser evil than Pashtun nationalism. If Obama is preparing to cut-and-run--which, fairly or unfairly, is how Pakistani generals will read his speech--then strengthening links to the Taliban will make Pakistan the dominant player in post-surge, post-withdrawal Afghanistan. The Taliban, too, will understand that, at best, they need only lay low, perhaps bloodying U.S. troops enough to keep the Afghanistan war unpopular among the Hollywood, university and media sets Obama cares about.

Obama is also wrong to believe that his surge will buy enough time to inject stability into Afghanistan's state or society. His inability to commit to the country's future will lead President Hamid Karzai to resist U.S. demands for reform. Obama's civilian "dream team" has turned into a nightmare. Special Envoy Richard Holbrooke's longing for the spotlight--and desire to create a High Commissioner to administer the country--has made the mercurial Karzai even more resistant to advice.

Victory in Afghanistan is crucial. Those who say occupation sparks insurgency misunderstand what is at stake. Afghans dislike occupation, but they place a higher priority on security. Security brings tolerance of the U.S. presence, and stability and a responsive government enables withdrawal. To cede the Taliban a safe haven, either now or post-surge, is unacceptable. Absent a stable government and a more capable Afghan National Army, the Taliban will fill the vacuum as they did from 1994 to 2001. The Taliban and their al-Qaida allies remain ideologically committed to the destruction of Western society. Not only will failure in Afghanistan mean a renewed threat to Americans across the globe, but it will also enable Islamists to convince more and more people that, having defeated two superpowers, they are the wave of the future. Unless Obama convinces the Taliban that his commitment to victory is unwavering, prepare for a dozen new Afghanistans.

Michael Rubin is a resident scholar at AEI.