Read a day-by-day account of the battle for control of key areas of Libya. And for the latest on what's next for Libya, the opposition and Moammar Gadhafi, tune in to "AC360º" at 10 p.m. ET Thursday on CNN.

Washington (CNN) -- The United States plans to send "purely humanitarian" disaster relief teams into eastern Libya, where rebels battling longtime strongman Moammar Gadhafi may be losing ground in that country's civil war, top U.S. officials said Thursday.

White House National Security Adviser Thomas Donilon told reporters that the U.S. Agency for International Development teams will be sent into monitor the delivery of humanitarian aid and should not be viewed as a military operation.

"It can in no way shape or form be seen as military intervention," Donilon said. The teams will assess that humanitarian aid is being delivered, he said, adding, "This is purely humanitarian to better assist in a humanitarian way the people of Libya."

Donilon's announcement came as officials in Washington, Europe and the Middle East are debating whether to aid rebel forces, who have been battling to topple Gadhafi since mid-February. But in a blunt assessment to Congress, National Intelligence Director James Clapper said Gadhafi's advantage in military force makes him likely to survive the revolt.

Clapper told the Senate Armed Services Committee that the rebels are "in for a tough row" against Gadhafi, who still commands warplanes, an air-defense network and loyal army brigades against the opposition forces. He cautioned that the situation is "very fluid," but added, "I think, longer term, the regime will prevail."

"I do believe Gadhafi is in this for the long haul," Clapper said. "I don't think he has any intention, despite some of the press speculation to the contrary, of leaving. From all evidence that we have -- which I'd be prepared to discuss in closed session -- he appears to be hunkering down for the duration."

The comment led to a call for Clapper's firing by a member of the committee, South Carolina Republican Lindsey Graham. In a statement issued after the hearing, Graham said the remarks were "not helpful to our national security interests."

But Clapper's assessment was backed up by Lt. Gen. Ronald Burgess, the head of the Defense Intelligence Agency. Burgess told senators that Gadhafi "seems to have staying power, unless some other dynamic changes at this time."

At NATO headquarters in Belgium, meanwhile, Secretary-General Anders Fogh Rasmussen said Thursday the allies are moving to beef up their naval presence off Libya to provide better surveillance and have discussed "initial options" for imposing a no-fly zone over the country in the event the U.N. Security Council approves one.

But Clapper warned that the Libyan network of radar and anti-aircraft batteries is "quite substantial," though some of the equipment has fallen into rebel hands. Libyan forces also have a large number of shoulder-fired missiles, "And, of course, there's great concern there about them falling into the wrong hands."

The Obama administration has called on Gadhafi, who took power in a 1969 coup, to step down. France recognized the newly created Libyan opposition movement as the sole representative of the country on Thursday. And Secretary of State Hillary Clinton told a House committee that Washington is "suspending" its ties to the Libyan Embassy and reaching out to opposition leaders "inside and outside of Libya."

The move effectively orders the embassy to close, though it stops short of breaking U.S.-Libyan diplomatic relations, a senior administration official told CNN.

"This is recognition that Gadhafi is no longer the legitimate leader of Libya, and therefore his representatives should leave," said the official, who was not authorized to speak on the record. Libyan Ambassador Ali Aujali abandoned Gadhafi last month, and the United States has not recognized his replacement, the official said.

Aujali met Thursday with Clinton, telling reporters afterward that they discussed whether the United States should recognize the Libyan rebels -- a move he said would "give us room to move, and to act, and to explain our views and to be received by different countries and different officials."

U.S. recognition is "very, very important," he said adding that Washington "needs "to stop Gadhafi and his family from killing our people."

Clinton plans to meet with some of those figures during a visit to Tunisia and Egypt next week, she told the House Appropriations Committee. And at the White House, spokesman Jay Carney said the United Strates is still assessing opposition group "to find out what their vision is, who they represent, what their ideas are and where they would take Libya in a post-Gadhafi future."

The U.S. Ambassador to Libya, Gene Cretz, apparently spoke to the head of the opposition's military council sometime after the revolt began, according to a recorded conversation played on Libyan state television Thursday. An opposition spokesman, Khaled Alsayeh, told CNN the call was intended to lay the groundwork for future communications, but the caller -- identified as Gen. Omar Hariri -- hung up before Cretz asked what equipment or support the rebels needed.

A U.S. official, who would not talk on the record because of the sensitivity of the issue, confirmed the authenticity of the call to CNN, but there was no indication when it was recorded. The State Department shuttered its embassy in Tripoli and evacuated U.S. diplomats in late February.

CNN's Pam Benson and Jill Dougherty contributed to this report.