The CIA is seeking authority to expand its covert drone campaign in Yemen by launching strikes against terrorism suspects even when it does not know the identities of those who could be killed, U.S. officials said.

Securing permission to use these “signature strikes” would allow the agency to hit targets based solely on intelligence indicating patterns of suspicious behavior, such as imagery showing militants gathering at known al-Qaeda compounds or unloading explosives.

The practice has been a core element of the CIA’s drone program in Pakistan for several years. CIA Director David H. Petraeus has requested permission to use the tactic against the al-Qaeda affiliate in Yemen, which has emerged as the most pressing terrorism threat to the United States, officials said.

If approved, the change would probably accelerate a campaign of U.S. airstrikes in Yemen that is already on a record pace, with at least eight attacks in the past four months.

For President Obama, an endorsement of signature strikes would mean a significant, and potentially risky, policy shift. The administration has placed tight limits on drone operations in Yemen to avoid being drawn into an often murky regional conflict and risk turning militants with local agendas into al-Qaeda recruits.

(Gene Thorp/The Washington Post)

A senior administration official, who like others spoke on the condition of anonymity to discuss sensitive internal deliberations, declined to talk about what he described as U.S. “tactics” in Yemen, but he said that “there is still a very firm emphasis on being surgical and targeting only those who have a direct interest in attacking the United States.”

U.S. officials acknowledge that the standard has not always been upheld. Last year, a U.S. drone strike inadvertently killed the American son of al-Qaeda leader Anwar al-Awlaki. The teenager had never been accused of terrorist activity and was killed in a strike aimed at other militants.

Some U.S. officials have voiced concern that such incidents could become more frequent if the CIA is given the authority to use signature strikes.

“How discriminating can they be?” asked a senior U.S. official familiar with the proposal. Al-Qaeda’s affiliate in Yemen “is joined at the hip” with a local insurgency whose main goal is to oust the country’s government, the official said. “I think there is the potential that we would be perceived as taking sides in a civil war.”

U.S. officials said that the CIA proposal has been presented to the National Security Council and that no decision has been reached. Officials from the White House and the CIA declined to comment.

Proponents of the plan said improvements in U.S. intelligence collection in Yemen have made it possible to expand the drone campaign — and use signature strikes — while minimizing the risk of civilian casualties.

They also pointed to the CIA’s experience in Pakistan. U.S. officials said the agency killed more senior al-Qaeda operatives there with signature strikes than with those in which it had identified and located someone on its kill list.

In Pakistan, the CIA “killed most of their ‘list people’ when they didn’t know they were there,” said a former senior U.S. military official familiar with drone operations.

The agency has cited the Pakistan experience to administration officials in arguing, perhaps counterintuitively, that it can be more effective against al-Qaeda’s Yemen affiliate if it doesn’t have to identify its targets before an attack. Obama, however, ruled out a similar push for such authority more than a year ago.

Increasing focus on Yemen

The CIA, the National Security Agency and other spy services have deployed more officers and resources to Yemen over the past several years to augment counterterrorism operations that were previously handled almost exclusively by the U.S. Joint Special Operations Command.

The CIA began flying armed drones over Yemen last year after opening a secret base on the Arabian Peninsula. The agency also has worked with the Saudi and Yemeni intelligence services to build networks of informants — much the way it did in Pakistan before ramping up drone strikes there.

The agency’s strategy in Pakistan was centered on mounting a drone campaign so relentless that it allowed no time between attacks for al-Qaeda operatives to regroup. The use of signature strikes came to be seen as critical to achieving that pace.

The approach involved assembling threads of intelligence from multiple sources to develop telltale “signatures” of al-Qaeda activity based on operatives’ vehicles, facilities, communications equipment and patterns of behavior.

A former senior U.S. intelligence official said the CIA became so adept at this that it could tell what was happening inside an al-Qaeda compound — whether a leader was visiting or explosives were being assembled, for example — based on the location and number of security operatives surrounding the site.

The agency might be able to replicate that success in Yemen, the former intelligence official said. But he expressed skepticism that White House officials, including counterterrorism adviser John O. Brennan, will approve the CIA’s request.

The situation in Pakistan’s tribal territory “is far less ambiguous than in Yemen,” the former official said. “Brennan has been deliberate in making sure targets we hit in Yemen are terrorist targets and not insurgents.”

As a result, the CIA has been limited to “personality” strikes in Yemen, meaning it can fire only in cases where it has clear evidence that someone on its target list is in a drone’s crosshairs.

Often, that requires information from multiple sources, including imagery, cellphone intercepts and informants on the ground.

Al-Qaeda in the Arabian Peninsula, or AQAP, as the Yemen-based group is known, has not been linked to a major terrorist plot since its failed attempt to mail parcels packed with explosives to addresses in Chicago in 2010. The death of Awlaki in a CIA drone strike last year is thought to have diminished the group’s ability to mount follow-on attacks.

But U.S. counterterrorism officials said that Awlaki’s death did not extinguish the group’s determination to attack the United States and noted that other key operatives — including Ibrahim Hassan al-Asiri, who designed the bombs used in the parcel plot — remain at large.

A quickening pace

The pace of U.S. airstrikes in Yemen is still far from the peak levels in Pakistan, but it is on a distinctly upward trend, with about as many strikes so far this year as in all of 2011.

Which U.S. entity is responsible for each strike remains unclear. In Pakistan, the CIA carries out every drone strike. But in Yemen, the United States has relied on a mix of capabilities, including drones flown by the CIA and the Joint Special Operations Command, as well as conventional military aircraft and warships parked off the coast.

The JSOC has broader authority than the CIA to pursue militants in Yemen and is not seeking permission to use signature strikes, U.S. officials said.

Obama administration officials have refused to provide details of how militants are targeted or to disclose the identities of those killed.

Asked to explain the surge in strikes this year, U.S. officials denied that there has been any change in authorities. Instead, they attributed the pace to intelligence-gathering efforts that were expanded several years ago but are only beginning to pay off.

“There has never been a decision to step up or down” the number of strikes, said a senior U.S. official involved in overseeing the Yemen campaign. “It’s all intelligence-driven.”

The Long War Journal, a Web site that tracks drone operations, estimates that there have been 27 strikes in Yemen since 2009 and that 198 militants and 48 civilians have been killed.

Awlaki was killed last September, six weeks after the CIA began flying armed drones over Yemen. This year, one senior AQAP operative has been killed: Abdul Mun’im Salim al Fatahani, who was suspected of involvement in the 2000 attack on the USS Cole in Yemen, was killed in January by a drone strike in Abyan province, according to the Long War Journal.

Staff writers Karen DeYoung and Julie Tate contributed to this report.