WASHINGTON — U.S.-born al-Qaida cleric Anwar al-Awlaqi, is the latest U.S. enemy wiped out by a furtive yet relentless and deadly assault on terror suspects on foreign soil stepped up by President Barack Obama.
The covert warfare, using military and CIA assets, drone strikes and other means has decimated al-Qaida's senior leadership and seriously degraded its capacity to mount operations against the United States, top U.S. officials say.
"We will be determined, we will be deliberate, we will be relentless, we will be resolute in our commitment to destroy terrorist networks that aim to kill Americans," a steely Obama said after an air raid in Yemen killed Awlaqi Friday.
But the strategy, sometimes unilateral, often in fractured nations where extremists seek to exploit lawless conditions to hide, also raises pressing new ethical, diplomatic and legal headaches for U.S. national security planners.
A string of U.S. drone strikes in Pakistan has for instance further antagonized always testy U.S. ties with Islamabad, amid a new row over alleged links between Inter Services Intelligence and the Haqqani network.
The relationship had already been rattled by the centerpiece of aggressive U.S. strategy — the U.S. special forces raid which killed al-Qaida chief Osama bin Laden in his hideout inside Pakistan in May.
Administration officials confided Friday that at least 23 senior extremist Islamic leadership figures had been killed or captured, in U.S. or allied operations in Pakistan, Somalia, Yemen and elsewhere since August 2009.
The organizations targeted included al-Qaida; Awlaqi's group, al-Qaida in the Arabian Peninsula; al-Qaida in East Africa; and Jemaah Islamiya of Indonesia.
Analysts said that the recent spate of killings reflected an evolving and aggressive strategy to snare terror suspects in areas once seen as havens.
"It is the marriage of better intelligence and better drone technology along with the increase in the local partnership of intelligence services that allows us to go after people individually," said Richard Fontaine, of the Center for a New American Security.
Tom Sanderson, of the Center for Strategic and International Studies, agreed that the latest spate of strikes reflected better intelligence and military expertise and a political impetus injected by the Obama White House.
"Counter-terrorism at the end of the Bush administration had become quite effective and Obama was smart to pick up where (Bush) left off and enhance it."
The result, Sanderson said was that the United States had now "injected risk" into calculations of terror networks, forcing operatives either to go into deep cover or flee, complicating their efforts to plot attacks.
All the signs point to an expansion of the operation, with the United States taking aim at a new generation of al-Qaida operatives and affiliates like the Al-Shebab group in Somalia.
John Brennan, Obama's top White House counter-terror adviser, pointed to new fronts in the war in a speech last month at Harvard.
"The United States does not view our authority to use military force against al-Qaida as being restricted solely to 'hot' battlefields like Afghanistan," Brennan said.
"We reserve the right to take unilateral action if or when other governments are unwilling or unable to take the necessary actions themselves."
But Brennan conceded that "international legal principles, including respect for a state's sovereignty and the laws of war, impose important constraints on our ability to act unilaterally and on the way in which we can use force in foreign territories."
The New York Times earlier quoted administration and congressional officials as saying that the Obama team was divided on the legal leeway the United States had in killing Islamist militants in Yemen and Somalia.
The paper said the discussion, pivotal to the future course of the anti-terror fight, centered on the extent to which Washington could escalate drone strikes, cruise missiles or commando raids from current high value al-Qaida targets to target thousands of extremist "foot soldiers."
Since the Bin Laden killing, suspected U.S. drone operations and other strikes have killed three senior AQAP operatives in Yemen and al-Qaida in East Africa senior leader Harun Fazul was killed in Somalia.
Other top leaders, including senior al-Qaida operative Atiyah Abd al-Rahman, and the group's chief of operations Abu Hafs al-Shahri have been killed in Pakistan's lawless tribal regions by U.S. drone strikes.
A number of other high ranking al-Qaida cadres have also been killed in the U.S. effort to dismantle al-Qaida's senior leadership and braintrust.