WASHINGTON – The CIA is secretly targeting Islamic extremists in Syria for possible lethal drone strikes as part of a contingency plan to protect the United States and its allies in the event the turmoil there worsens, current and former U.S. officials say.

President Obama has not authorized drone missile strikes in Syria, and none are under consideration.

But the CIA effort, which involves assembling detailed dossiers on key militants, gives the White House both lethal and nonlethal options if it concludes that Syria’s 2-year-old civil war is creating a new haven for terrorists. The intelligence files also could be used to help moderate opposition figures prevail over extremists.

The Counter Terrorism Center, which runs the CIA’s covert drone killing program in Pakistan and Yemen, recently shifted several targeting officers to improve intelligence collection on militants in Syria who could pose a terrorist threat, the officials said.

The targeting officers have formed a unit with colleagues who were tracking al-Qaida operatives and fighters in Iraq. U.S. officials believe that some of these operatives have moved to Syria and joined Islamic militias battling to overthrow President Bashar Assad.

The targeting is part of an array of CIA and Pentagon responses and contingency plans as the Syrian bloodletting steadily worsens, threatening regional stability. Other proposals include plans to seize or destroy Syria’s chemical weapons stockpiles, which are closely monitored by U.S. intelligence, to prevent their misuse.

The targeting officers focusing on Syria are based at CIA headquarters in Langley, Va., officials said. The agency has not deployed many American operatives into the war zone, but it works closely with Saudi, Jordanian and other regional spy services active there. CIA officers meet with Syrian rebel leaders in Turkey and Jordan, current and former officials say.

The increased U.S. effort comes as radicalized Islamic fighters have won a growing share of rebel victories. The State Department says one of the strongest militias, Al Nusra Front, is a terrorist organization that is indistinguishable from the group al-Qaida in Iraq.

Amnesty International reported Thursday that some Syrian opposition fighters routinely executed captives and suspected informants, although the group said Assad’s security forces were even more brutal.

At least in public, the White House has limited the U.S. role in the war to sending food and medical supplies to rebels, as well as aid to nearby countries that have taken in nearly 1 million refugees. U.S. allies are providing weapons and ammunition to the rebels, but Obama so far has objected to proposals for more aggressive U.S. intervention.

CIA targeting officers normally assemble bits of intelligence to create folders known as “targeting packages,” for a variety of reasons.

They can be used if policymakers determine further surveillance, arrest or other action is warranted.

The CIA has created nonlethal targeting packages, for example, for drug cartel leaders in Mexico and nuclear scientists in Iran. The agency views skilled targeting officers as critical to almost any current intelligence operation.

Nada Bakos, a former CIA targeting officer who helped track down Abu Musab Zarqawi, the al-Qaida in Iraq leader who was killed by U.S. forces in 2006, said the intense focus entailed “trying to figure out what they are doing and how to go about stopping it.”