President Bush departs for Africa today, following several weeks' worth of debate about U.S. intervention in war-torn Liberia. Unfortunately, the Pentagon's reluctance to commit troops to what it perceives as an errand of mercy has obscured one of the most promising developments in Africa policy since the end of the Cold War. Despite ingrained assumptions about the continent's strategic irrelevance, the Defense Department has begun to recognize that U.S. security interests in Africa--with its failed states, porous borders, proximity to the Persian Gulf and large, impoverished population of Muslims--cannot be ignored.

Less than a decade after the United States abandoned Somalia to Islamic fundamentalists and turned a blind eye to genocide in Rwanda, American soldiers are returning to Africa--and not just for peacekeeping.

Initial attention has focused on East Africa, where Osama bin Laden lived during the 1990s and where al Qaeda has perpetrated several attacks. Over the past year, the Bush administration has quietly dispatched 1,800 troops to Djibouti, a small country on the Horn of Africa, and established America's first long-term, sub-Saharan military base there. The mission, known as Combined Joint Task Force Horn of Africa, is responsible for detecting, disrupting and defeating the agents of terrorism in six East African countries, as well as Yemen. Whether working to capture an Al Qaeda operative in Somalia, securing Kenya's borders against would-be infiltrators or conducting reconnaissance on suspected terrorist training camps in Sudan, U.S. military power is being projected across the region as never before.

Part of a broader, global realignment of U.S. forces, the basing of American soldiers in East Africa marks a landmark shift in the Pentagon's thinking about a part of the world that, for too long, we have considered unworthy of hard power calculus. It is, furthermore, a transformation that is only just beginning.

Most of Africa falls under U.S. European Command, led by Gen. James Jones, who has been outspoken about the continent's potential as a "terrorist breeding ground" and "melting pot for the disenfranchised of the world." He is especially concerned about the possible convergence of Islamic fundamentalism and oil wealth in West Africa, which may someday provide the United States with as much as a quarter of its oil.

For these reasons, the Pentagon is likely in the coming years to acquire or expand basing rights in a host of African countries, rotating troops through some sites and pre-positioning material at others. Gen. Jones has said that he would like to see Navy carrier groups and Marine expeditionary units spend less time in the Mediterranean and more time patrolling the West African coast. There is even talk that a mission similar to the Horn of Africa task force could be established somewhere in West Africa to deal with the ungoverned wastelands that extend across northern Mali and southern Algeria, where Islamic terrorists may be lurking.

To be sure, U.S. military commitments in Africa remain uneven. The Bush administration has made no serious effort to inject American power into the internecine war in Congo that has killed more than 3 million people. Instead, we have delegated responsibility to a feckless, French-led stabilization effort, following the failure of its feckless, U.N.-led predecessor. The Pentagon's aversion to peacekeeping in Liberia, despite the brutality that its warlord president has inflicted on the region, suggests that the expansion of U.S. power in Africa will remain for now focused primarily on security, not humanitarian concerns.

But these interests cannot be so easily separated. In 1993, a still-embryonic al Qaeda--heady from victory against the Soviets in Afghanistan--trained operatives to attack the U.S. peacekeeping force in Somalia. It was al Qaeda's first challenge to the American colossus, and Washington folded; why risk soldiers' lives, after all, when Africa doesn't matter? As a consequence, bin Laden's messianic vision emerged more credible than ever, and five years later, Africa became the scene of al Qaeda's first large-scale attack: the simultaneous bombings of U.S. embassies in Kenya and Tanzania.

As American policymakers come to appreciate Africa's strategic importance, they will no doubt pay better attention to its other problems. As the United States builds bases and adopts commitments on the ground, future interventions (regardless of their motivation) will be logistically and conceptually easier for the Pentagon to assume--and harder for politicians to avoid.

Some will no doubt view the establishment of U.S. bases in Africa as yet another sign of American militarism and hegemony. In fact, it is simply sensible policy. Of course, mutual defense pacts and military installations cannot reduce rates of HIV infection or create a workable economy; but neither can development aid depose authoritarian thugs or transnational terrorists. It is for this reason that American power is coming to Africa--and not a second too soon.

Thomas Donnelly is a resident fellow and Vance Serchuk a researcher at American Enterprise Institute.