US intelligence operatives were on the ground in Libya before President Barack Obama signed a secret order authorizing covert support for anti-Gaddafi rebels, US government sources said.
The CIA personnel were sent in to contact opponents of Libyan leader Muammar Gaddafi and assess their capabilities, two US officials said.
"They're trying to sort out who could be turned into a military unit and who couldn't," said Bob Baer, a former CIA case officer whose memoirs were turned into the Hollywood thriller "Syriana."
Baer said that the US operatives most likely entered Libya on the ground through neighboring Egypt and are lightly equipped.
The president -- who said in a speech on Monday "that we would not put ground troops into Libya" -- has legal authority to send US intelligence personnel without having to sign a covert action order, current and former US officials said.
Within the last two or three weeks, Obama did sign a secret "finding" authorizing the CIA to pursue a broad range of covert activities in support of the rebels.
Congressional intelligence committees would have been informed of the order, which the officials said came after some CIA personnel were already inside Libya.
Neither the CIA nor the White House have commented directly on US undercover operations and plans in Libya.
"I will not and cannot discuss intelligence matters," White House spokesman Jay Carney said on Thursday. "What the president has made clear is that he will not send, has not sent and will not send American troops on the ground into Libya."
One US government source familiar with Libya policy said the Obama administration is considering plans under which US special forces personnel experienced in training anti-Taliban forces in Afghanistan would work with CIA officers in efforts to organize and train Libyan opposition fighters.
While such plans have not been put into operation, they are fairly advanced, the source said. There is no indication the plans have been sent to the White House for consideration by Obama.
The government source said some planners are concerned that any operation involving special forces would cut into their scheduled rest periods and ultimately might lead highly skilled but exhausted operatives to leave government service.
Defense secretary Robert Gates, in testimony to Congress on Thursday, declined to comment on any CIA activity in Libya.
The rebels need training and organization, he said, but this was "not a unique capability for the United States. And, as far as I'm concerned, somebody else should do that."
Gates said US agencies "don't have much visibility into those who have risen against Gaddafi." Admiral Mike Mullen, chairman of the Joint Chiefs of Staff, told lawmakers there are only about 1,000 rebels with any military training.
"Mother may I"
Other US officials familiar with Obama's covert action order said while it authorizes a potentially sweeping range of measures to support Libyan rebels, each specific operation -- for example, sending in US trainers, money or weapons -- would require further "permissions" from the White House.
Former officials say these subsidiary authorizations are known in intelligence circles as "Mother may I findings."
A former US official said covert action findings are required only for the authorization of CIA operations directed at "influencing" events in a target country.
"You don't need a finding to send in agency folks to gather intelligence," the former official said.
US officials said the first Western undercover operatives to be sent into Libya, around the time US and some European forces began air strikes under a UN Security Council mandate, were not American.
The New York Times reported that "dozens" of British special forces soldiers and officers from Britain's foreign intelligence agency, known as MI-6, are working inside Libya.
It said that a former British official briefed on current operations said dozens of soldiers from the Special Air Service and Special Boat Service commando units had been sent into Libya and their assignments included locating where Gaddafi's forces had deployed surface-to-air missiles.
But British government sources contacted said they could not confirm the report and downplayed the role of British special forces early in the Libyan operation.
One European official noted that British and US military and intelligence services traditionally maintain very close ties and often operate as partners.
Some congressional leaders are questioning the wisdom of US engagement with Libyan rebels.
Ileana Ros-Lehtinen, Republican chairwoman of the House of Representatives Foreign Affairs Committee, said, "My constituents are asking me, Just who are we helping and are we sure they are true allies who won't turn and work against us?"