Is it time to declare Mission Accomplished in Afghanistan, as former State and Defense department official Leslie Gelb and others suggest? Gelb argues that the killing of Osama bin Laden was a game-changer that dramatically reduces the need for a large force in Afghanistan. We could afford to cut the existing force to as low as 15,000 troops in two years, Gelb wrote in The Wall Street Journal. Many on the right agree. Given the expense, our huge national debt and the continued risk to our troops, we can greatly reduce our involvement much quicker than expected, they argue. President Barack Obama, however, should proceed with great caution. Its still too early to gauge the effect of bin Ladens absence on the Taliban and on Al-Qaeda. If theres evidence in the combat zone that the SEALs successful raid has materially demoralised the enemy, then Washington can act accordingly and accelerate withdrawals. Afghanistan is one place where Obama has lived up to his promise to govern as a wise moderate. He approved a substantial troop surge, and his decision to send the SEALs after bin Laden was a courageous one. He must now deflect pressure for a too-rapid troop drawdown, which would run the risk of another security vacuum opening up in a combat theatre our troops have fought for 10 years to secure. After all, the mission Obama assigned the military was to disrupt, dismantle and defeat Al-Qaeda in Afghanistan and Pakistan, and to prevent its capacity to threaten America and our allies in the future. Returning Afghanistan to the Taliban would do precisely the opposite. Many point to chaotic places such as Somalia and Yemen countries that are potential or current safe harbours for Al-Qaeda and ask why we dont inject troops there as well. Its a way of raising questions about our heavy involvement in Afghanistan. But Afghanistan is different, as Obama recognised in his mention of Pakistan in the mission statement. The latter country is riven by internal discord and faces a stubborn insurgency of its own. A too-hasty US withdrawal would almost certainly result in the fall of the Karzai government, with the likely return of the Taliban. Al-Qaeda would have an opportunity to move in and reconstitute its strength, along with militant groups bent on the overthrow of Pakistan. Afghanistan would again become a base not only for attacks on the United States but on its neighbour. It is the proximity to Pakistan that makes Afghanistan a problem wholly different from a Yemen or a Somalia. Lose Afghanistan and you run the risk of losing Pakistan. Our troops may be able to move more quickly than expected to a largely advisory role. But such a move shouldnt be rushed solely because of the bin Laden raid. As Stephen Biddle of the Council on Foreign Relations noted in testimony prepared for the Senate Foreign Relations Committee, most terrorist groups survive the loss of their leader. Al-Qaedas affiliate in Iraq continued bombing and killing after the takedown of Abu Musab al Zarqawi. Israeli strikes against the leadership of Hamas and Hezbollah havent destroyed either group. Yes, there are exceptions: Shining Path in Peru and Aum Shinriko in Japan both faded after their leaders arrests. Biddle acknowledges that Al-Qaeda could prove one of the exceptions, given that it already seemed in general decline, thanks in large part to its indiscriminate killing of other Muslims. Al-Qaedas role in the Arab Spring uprisings has been virtually nonexistent. But its too early to tell, and the perception of an America perpetually on the verge of leaving encourages Afghans to hedge their bets. Biddle writes of the reaction among Afghans after 2009, when Obama coupled his troop-surge announcement with a pledge to begin withdrawing in only 18 months. Many Afghans, Biddle wrote, misinterpreted the presidents speech to mean that there would be no US troops remaining in Afghanistan by 2012. This perception was remarkably stubborn; in a 2010 visit to Kabul, I found even members of Afghanistans Parliament and analysts from Afghan think tanks convinced that we would be gone by 2012. McClatchy