WASHINGTON — Before ceding power, the Obama administration quietly removed a former extremist stronghold in Libya from a list of combat zones where United States counterterrorism drone strikes are authorized without obeying special rules intended to prevent civilian deaths, officials said on Friday.
The change means that as Donald J. Trump’s presidency begins, the United States is targeting Islamist militants in three known “areas of active hostilities,” where strict guidelines to protect civilians do not apply: Afghanistan, Iraq and Syria. For much of 2016, there was a fourth: The region around Surt, Libya.
It is not clear whether Mr. Trump will keep those civilian-protection rules — called the “Presidential Policy Guidance,” or P.P.G. — for airstrikes outside of active war zones. Issued by Mr. Obama in 2013, they require “near certainty” that a bombing will kill no civilians, and that the target must pose a threat to Americans — not just to American interests.
The Obama administration developed the guidelines in response to criticism that airstrikes were killing too many civilians, and in turn fueling anti-Americanism and helping terrorists recruit new members. But some military and C.I.A. officials have chafed under the limits.
Mr. Trump’s team has not said what it will do with the 2013 rules. But a statement posted on the White House website after he was sworn in on Friday said the new administration would “pursue aggressive joint and coalition military operations when necessary” to defeat the Islamic State.
Last August, after the fledgling Libyan government asked for help in dislodging militants from the city of Surt, the Obama administration quietly designated it an “area of active hostilities,” where the guidelines to prevent civilian deaths did not apply. The change gave the military a freer hand to target Islamic State fighting positions and equipment. Under ordinary combat rules established by the laws of war, some bystander deaths are permissible if deemed necessary and proportionate.
At the time, the government did not announce that Mr. Obama had exempted Surt from the extra safeguards established by the 2013 rules. The New York Times first reported the change in late November.
Between August and December, the military said it carried out 435 airstrikes to drive out the Islamic State from Surt, a campaign called Operation Odyssey Lightning. It concluded the campaign on Dec. 19.
But Mr. Obama this week briefly turned Odyssey Lightning back on, and expanded its geographic scope, to authorize a major airstrike on Jan. 19 against suspected Islamic State training camps in the desert about 25 miles southwest of Surt. The bombings killed more than 80 militants, the military said. It did not report any civilian deaths, but said it was still evaluating the results.
In response to questions from The Times on Friday, officials at the Pentagon said that when Odyssey Lightning ended last month, so also did the military’s authority to carry out airstrikes in Surt without obeying the 2013 rules. But when Mr. Obama briefly revived the operation for the strikes this week, its exemption from those rules was temporarily turned back on too, they said.
Col. Mark Cheadle, a spokesman for the United States Africa Command, said the expanded targeting authority expired again at midnight between Jan. 19 and Jan. 20, and now “there are no more” areas in Libya where the 2013 rules do not apply.
The administration had offered a clue that Surt was no longer exempted from the 2013 rules in a report the Office of the Director of National Intelligence issued late Thursday.
The report summarized official estimates of militants and civilians killed last year in counterterrorism airstrikes where the 2013 safeguards generally applied. But it also mentioned that areas of active hostilities, where the protections do not apply, currently include Afghanistan, Iraq, and Syria. It made no mention of Libya.
The report also said that in 2016, the United States carried out 53 such airstrikes that killed between 431 and 441 militants and one civilian. Those figures apparently include a huge airstrike in Somalia in March that killed about 150 people at what the military said was a graduation ceremony for Islamist fighters.
The government disclosed Thursday’s report under an executive order Mr. Obama issued last July requiring annual public disclosure of casualty estimates from counterterrorism airstrikes away from active-hostilities zones. That order was part of a broader effort late in Mr. Obama’s tenure to make the government less secretive about drone strikes. It is also not clear whether Mr. Trump will keep that requirement.