The killing of the U.S.-born al-
Qaeda cleric Anwar Al-Awlaki on Friday along with another U.S. citizen and two other al-Qaeda operatives in Yemen is likely to fuel the international controversy over the legality and wisdom of the Obama administration’s dramatically increased use of drone attacks. For several years, U.S. allies have made no public comment even as U.S. drone strikes have killed twice as many suspected al-Qaeda and Taliban members than were ever imprisoned in Guantanamo Bay. But that acquiescence may change, as human rights groups and the media focus more attention on the legality and collateral damage of drone attacks. The U.S. drone program has been highly effective in killing senior al-Qaeda leaders, but the administration needs to work harder to explain and defend its use of drones as lawful and appropriate — to allies and critics — if it wants to avoid losing international support and potentially exposing administration officials to legal liability.

The U.S. position, under the George W. Bush and Obama administrations, has been that drone strikes against al-Qaeda and Taliban leaders are lawful under U.S. and international law. They are permitted by the September 2001 Authorization to Use Military Force Act, which empowered the president to “all necessary and appropriate force” against nations, organizations or persons who planned, committed or aided the Sept. 11 attacks.

The United States also believes that drone strikes are permitted under international law and the United Nations Charter as actions in self-defense, either with the consent of the country where the strike takes place or because that country is unwilling or unable to act against an imminent threat to the United States. U.S. officials have been understandably reluctant to confirm whether consent has been given by particular countries.

Obama administration officials have explained in the past that strikes against particular militant leaders are permissible, either because the individuals are part of the overall U.S. conflict with al-Qaeda or because they pose imminent threats to the United States. President Obama emphasized Awlaki’s operational role on Friday, stating that he was the “leader of external operations for al-Qaeda in the Arabian Peninsula.”

The killing of Awlaki raises additional legal concerns because U.S. citizens have certain constitutional rights wherever they are in the world. Some human rights groups have asserted that due process requires prior judicial review before killing an American, but it is unlikely that the Constitution requires judicial involvement in the case of a U.S. citizen engaged in terrorist activity outside this country. Administration lawyers undoubtedly reviewed the targeting of Awlaki even more carefully than of a non-American, and the Justice Department reportedly prepared an opinion concluding that his killing would comply with domestic and international law. This is likely to be considered sufficient due process under U.S. constitutional standards.

But the U.S. legal position may not satisfy the rest of the world. No other government has said publicly that it agrees with the U.S. policy or legal rationale for drones. European allies, who vigorously criticized the Bush administration for asserting the unilateral right to use force against terrorists in countries outside Afghanistan, have neither supported nor criticized reported U.S. drone strikes in Pakistan, Yemen and Somalia. Instead, they have largely looked the other way, as they did with the killing of Osama bin Laden.

Human rights advocates, on the other hand, while quiet for several years (perhaps to avoid criticizing the new administration), have grown increasingly uncomfortable with drone attacks. Last year, the U.N. rapporteur for summary executions and extrajudicial killings said that drone strikes may violate international humanitarian and human rights law and could constitute war crimes. U.S. human rights groups, which stirred up international opposition to Bush administration counterterrorism policies, have been quick to condemn the Awlaki killing.

Even if Obama administration officials are satisfied that drone strikes comply with domestic and international law, they would still be wise to try to build a broader international consensus. The administration should provide more information about the strict limits it applies to targeting and about who has been targeted. One of the mistakes the Bush administration made in its first term was adopting novel counterterrorism policies without attempting to explain and secure international support for them.

White House counterterrorism adviser John Brennan rightly acknowledged in a recent speech that “the effectiveness of our counterterrorism activities depends on the assistance and cooperation of our allies.” If the Obama administration wants to avoid losing the tacit support (and potentially the operational and intelligence assistance) of its allies for drone strikes and its other counterterrorism policies, it should try to ensure that they understand and agree with the U.S. policy and legal justification. Otherwise, the administration risks having its largely successful drone program become as internationally maligned as Guantanamo.

The writer is a partner at Arnold & Porter LLP and an adjunct senior fellow in international and national security law at the Council on Foreign Relations. He served as legal adviser for the State Department from 2005 to 2009 and as legal adviser to the National Security Council from 2001 to 2005.