On May 26, unknown assailants attacked a border post in Uzbekistan's volatile Fergana Valley. Less than 24 hours later, a suicide bomber blew himself up in the nearby city of Andijan, killing a policeman. Both attacks were claimed by a shadowy group of Islamist militants with ties to the Taliban and al Qaeda.

Although post-Soviet Central Asia has seen little terrorism in recent years, the attacks are a reminder that the conflicts underway in Afghanistan and Pakistan have a regional dimension -- and that the stepped-up U.S. involvement in the region carries the risk that instability will spread to other countries. While the fight against Islamist extremism may already seem dauntingly wide-ranging and complex, the Obama administration's thinking is not complicated enough. It's time to stop ignoring the Central Asian dimension of this conflict.

The U.S. presence in the region has already begun to expand. In the face of mounting instability in Pakistan, the U.S. military has increasingly turned to post-Soviet Central Asia as an alternative route for shipping supplies to Afghanistan. Kyrgyzstan is currently Washington's major transit point, but, under pressure from Moscow, the Kyrgyz government has ordered U.S. troops to abandon their air base at Manas by August. The Kyrgyz might still experience a change of heart, but the United States has recently reached out to Uzbekistan as a possible alternative.

The most religiously conservative region of Central Asia, the Fergana Valley (a region that, thanks to Stalinist gerrymandering, encompasses parts of Kyrgyzstan and Tajikistan as well as Uzbekistan) has long been a center of opposition to the repressive regime of Uzbek President Islam Karimov. Although most opposition is peaceful, the valley has nurtured militants in the past, notably the Islamic Movement of Uzbekistan (IMU), which conducted a series of large-scale attacks against the government in the late 1990s. In the ensuing crackdown, IMU sympathizers fled to neighboring states. Several went to Tajikistan, where they were protected by the Tajik authorities and Russian security personnel as a means of exerting leverage against Karimov.

Others ended up in Afghanistan, where they forged close ties with both the Taliban and al Qaeda before their ranks were decimated by U.S. bombing during the invasion of Afghanistan. The survivors fled once again, many to Pakistan's volatile tribal regions, where they were sheltered by the Pakistani Taliban. These Uzbek refugees have played a central role in the recent unrest engulfing Swat and neighboring regions of Pakistan. Now there is evidence that Islamabad's offensive is forcing the Uzbeks back into Central Asia. Analysts in the region fear that the recent attacks in the Fergana Valley are the work of fighters fleeing Pakistan.

The militants' displacement from Pakistan would be a boon to Islamabad's effort to assert its sovereignty over the entirety of its territory. At the same time, it risks opening a dangerous new phase in the war, especially as Central Asian governments distrust one another and are ill-prepared to deal with an influx of battle-hardened Islamist militants. For the United States, the decision to increase troop levels in Afghanistan makes the Central Asian supply route increasingly vital and increases the risk that the war effort could be hamstrung by the spread of instability.

U.S. President Barack Obama is right that the conflict in Afghanistan cannot be won without addressing the problems of Pakistan. However, his "Af-Pak" strategy is incomplete. It requires a fuller appreciation of how the conflict's tentacles reach into post-Soviet Central Asia and a strategy for checking the spread of Taliban-style militancy to Uzbekistan and its neighbors.

Washington is shipping some supplies through Russia, but cannot risk complete dependence on Moscow for transit to Afghanistan. For now, the administration has little choice but to rely on Central Asia, but it must do more to help the region address its own problems with extremism. Rather than just forging military alliances, Washington needs to engage more deeply to address the social problems that feed militancy, especially in the Fergana Valley. Unemployment and lack of opportunity are the biggest sources of frustration.

In addition to military facilities, the United States should provide money for schools and job training. To the extent possible, it should also cooperate with regional governments to improve the investment climate and encourage foreign companies to move into the region. It should also work with the governments of Uzbekistan, Kyrgyzstan, and Tajikistan to resolve their border disputes in the Fergana Valley and address the mistrust that prevents them from adopting a united front against the militants.

The Uzbek militants' apparent flight from Pakistan represents progress in one phase of the struggle against extremism. To succeed in the next phase, the United States needs a regional strategy that recognizes how Central Asia is inextricably linked to the problems of "Af-Pak."