WASHINGTON -- The U.S. will keep targeting al-Qaida anywhere in the world, including in countries unable or unwilling to do it themselves, the top U.S. counter terror official said Friday.

White House counter terror chief John Brennan laid out what could be called the Osama bin Laden raid doctrine, in remarks at Harvard Law School. He says under international law, the U.S. can protect itself with pre-emptive action against suspects the U.S. believes present an imminent threat, wherever they are.

That amounts to a legal defense of the unilateral Navy SEAL raid into Pakistan that killed al-Qaida mastermind bin Laden in May, angering Pakistan. It also explains the thinking behind other covert counterterrorist action, like the CIA’s armed drone campaign that only this week killed a top al-Qaida operative in Pakistan’s tribal areas. The Obama administration has quadrupled drone strikes against al-Qaida targets since taking office.

The Obama administration has more recently expanded drone strikes and the occasional special-operations raid into areas like Somalia, where the weak government may be willing to fight al-Qaida but lacks the resources. Navy SEALs targeted al-Qaida operative Saleh Ali Saleh Nabhan in Somalia in 2009, by helicopter. The SEALs then landed to pick up his body and bury it at sea, just as bin Laden was later interred.

“We reserve the right to take unilateral action if or when other governments are unwilling or unable to take the necessary actions themselves,” Brennan said.

Yet Brennan followed that by saying that does not mean the U.S. can use military force “whenever we want, wherever we want. International legal principles, including respect for a state’s sovereignty and the laws of war, impose important constraints on our ability to act unilaterally.”

Brennan did not explain how that constraint applied, when the U.S. Navy SEALs entered Pakistani territory to go after Bin Laden, without Pakistani government knowledge or permission.

He said the U.S. prefers to work with the governments of countries where the targets hide, as it does in Yemen. The U.S. has expanded counterterrorist cooperation with the Yemeni government, which allows the U.S. to fly armed drones, and other types of surveillance, pairing U.S. special operations forces with its own troops, and even conducting the occasional air strike, fired from a ship offshore, or dropped from a jet.

The senior counterterrorist official said the U.S. prefers to capture rather than kill terror suspects whenever possible, an apparent answer to critics who allege the administration has authorized the killing of terrorists as it has no place to hold them, with the status of the Guantánamo Bay detention facility still in limbo.

“It is the unqualified preference of the administration to take custody of that individual so we can obtain information,” he said.

The Pentagon currently houses 171 captives at the Navy base in southeast Cuba, four of them convicts serving out war crimes sentences on a special cellblock of a maximum security prison. The Bush administration made its last transfer there in March 2008, and the Obama administration has never sent a captive there for interrogation or detention.

Brennan reiterated the administration’s commitment to prosecuting terror suspects in federal courts, but reserved the right to try them by military commissions – a position that offends both the Obama administration’s leftist base, which wanted military commissions ended, and many top Republican officials who do not want to grant terror suspects the same rights as U.S. citizens, by trying them inside the U.S.