Representative Mike Rogers, a Michigan Republican who leads the House Intelligence Committee, said Wednesday that he opposed arming the rebels. “We need to understand more about the opposition before I would support passing out guns and advanced weapons to them,” Mr. Rogers said in a statement.

Because the publicly stated goal of the Libyan campaign is not explicitly to overthrow Colonel Qaddafi’s government, the clandestine war now going on is significantly different from the Afghan campaign to drive the Taliban from power in 2001. Back then, American C.I.A. and Special Forces troops worked alongside Afghan militias, armed them and called in airstrikes that paved the rebel advances on strategically important cities like Kabul and Kandahar.

In recent weeks, the American military has been monitoring Libyan troops with U-2 spy planes and a high-altitude Global Hawk drone, as well as a special aircraft, JSTARS, that tracks the movements of large groups of troops. Military officials said that the Air Force also has Predator drones, similar to those now operating in Afghanistan, in reserve.

Air Force RC-135 Rivet Joint eavesdropping planes intercept communications from Libyan commanders and troops and relay that information to the Global Hawk, which zooms in on the location of armored forces and determines rough coordinates. The Global Hawk sends the coordinates to analysts at a ground station, who pass the information to command centers for targeting. The command center beams the coordinates to an E-3 Sentry Awacs command-and-control plane, which in turn directs warplanes to their targets.

Lt. Gen. David A. Deptula, who recently retired as the Air Force’s top intelligence official, said that Libya’s flat desert terrain and clear weather have allowed warplanes with advanced sensors to hunt Libyan armored columns with relative ease, day or night, without the need for extensive direction from American troops on the ground.

But if government troops advance into or near cities in along the country’s eastern coast, which so far have been off-limits to coalition aircraft for fear of causing civilian casualties, General Deptula said that ground operatives would be particularly helpful in providing target coordinates or pointing them out to pilots with hand-held laser designators.

The C.I.A. and British intelligence services were intensely focused on Libya eight years ago, before and during the successful effort to get Colonel Qaddafi to give up his nuclear weapons program. He agreed to do so in the fall of 2003, and allowed C.I.A. and other American nuclear experts into the country to assess Libya’s equipment and bomb designs and to arrange for their transfer out of the country.