WASHINGTON — The CIA has stepped up secret contingency planning to protect the United States and its allies as the turmoil expands in Syria, including collecting intelligence on Islamic extremists for the first time for possible lethal drone strikes, according to current and former U.S. officials.

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

The Counterterrorism 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 Qaeda 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 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 — which has caused 70,000 deaths, according to United Nations estimates — is creating a haven for terrorists. The intelligence files also could be used to help opposition figures with moderate views prevail over extremists.

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 Qaeda 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.

The CIA and the White House declined requests for comment Friday on the targeting effort.

CIA targeting officers normally assemble bits of intelligence — including agent reports, cellphone intercepts, video footage, public records, tips from foreign spy services — 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 Qaeda 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."

Identifying possible threats in Syria would be "a logical step if the policy community sends a signal that, 'Hey, you guys might want to think about how you would respond to a possible request for plans about how you would thin the herd of the future insurgency,'" said a former CIA officer with experience in the Middle East.

U.S. lethal action in Syria is not unprecedented. In October 2008, the CIA and U.S. special operations forces conducted a helicopter assault across the Iraqi border into eastern Syria. The raid killed Abu Ghadiya, a logistics commander for Al Qaeda who allegedly smuggled weapons, money and foreign fighters from Syria into Iraq during the insurgency there.

No evidence suggests the CIA or Pentagon has launched airstrikes against Al Qaeda militants in Iraq since U.S. troops withdrew in December 2011. But some extremists have joined militias in Syria and aspire to attack U.S. facilities or allies, officials said.

In October, Jordanian authorities announced the arrest of 11 people with connections to Al Qaeda in Iraq on suspicion of plotting a major terrorist attack. They said the group's targets included the U.S. Embassy in the Jordanian capital, Amman.

Some former CIA officials expressed skepticism about any idea of using armed drones in Syria. There is no evidence, they said, that Syrian militants pose a threat to the U.S. homeland.

"If we do this, why don't we start droning people in Hezbollah?" asked a former CIA officer who worked in Iraq, referring to the Lebanon-based militant group that Washington considers a terrorist organization. "It opens the door for a lot of other things."