DRONES HAVE become a game-changing technology in the fight against terrorism. Before 2001 U.S. commanders could not reliably target al-Qaeda’s training camps in Afghanistan, much less the group’s top commanders. But some 2,000 militants have now been killed by drones, including several deputies to Osama bin Laden. The Obama administration, which has sharply escalated the use of drones in Pakistan’s tribal territories, is moving to expand their use in Yemen and Somalia. According to a report last week in The Post, drone bases have been established or are under construction in Djibouti, Ethi­o­pia, the Seychelles and on the Arabian Peninsula.

The drone war expansion has been accompanied by debate within the administration about the legal propriety of attacking targets outside Afghanistan and Pakistan. One question is whether Yemen and Somalia can be treated as “hot” battlefields covered by Congress’s 2001 authorization of the use of force against al-Qaeda and by the international principle of self-defense; in a Sept. 16 speech White House counterterrorism adviser John Brennan arguedthat they can be. A related question is whether strikes must be directed only at those plotting against the United States, or if rank-and-file militants and training camps can be struck, as in Pakistan.

In our view the legal situation is straightforward. It’s been clear for more than a decade that al-Qaeda is a transnational organization that seeks to wage war against the United States from multiple foreign bases; especially in areas where national sovereignty has broken down, a U.S. military response is justified. It would be helpful if Congress would clarify this by passing legislation that renews the authorization of military force and stipulates that it can be used against al-Shabab and other al-Qaeda branches.

The harder question is whether the administration’s increasing reliance on drones is weakening what should be a much broader strategy. While militants can and should be picked off by targeted strikes in Yemen and Somalia, neither country will cease to be a source of terrorism until it can be stabilized under a responsible government. The United States has been trying to encourage a political settlement in Yemen that would end months of near-anarchy, and has been helping to fund and train Somalia’s transitional government and security forces. But the efforts have been underfunded and underambitious.

In Pakistan, the administration has presented military leaders and the shaky government with “what amounts to an ultimatum,” The Post’s Karen DeYoung reported: Either cut ties with a Taliban group that recently staged an attack on the U.S. embassy in Kabul, or the United States will act against it unilaterally. Drones make it easier to carry out that threat. But the administration must weigh any expansion of drone strikes against the need to maintain a relationship with Pakistan and promote its moderate political forces in what has become a fateful domestic power struggle.

Drones will remain invaluable to preventing terrorist attacks against U.S. targets. But they cannot become a substitute for sustained efforts at nurturing moderate and representative government in the Muslim world. That is as true in Yemen and Somalia as it is in Afghanistan and Pakistan.