Washington: U.S. commanders moved ships and planes closer to Libya on Monday, but analysts said military action against Muammar Gaddafi was unlikely even as Washington steps up its rhetoric against the Libyan leader.

Richard Downie, a fellow at the Center for Strategic and International Studies in Washington, said past experiences in Africa, such as Somalia in the 1990s, had left Washington reluctant to engage in ground missions on the continent.

"The United States is wary of getting involved in a very messy, hard-to-interpret situation like this," he said, adding there would have to be 'a significant ratcheting up' of events in Libya before military action might happen.

Pentagon spokesman Colonel David Lapan said military planners were working on 'various contingency plans' but he gave no details about the number and location of the ships and planes being moved closer to Libya, where opposition forces and protesters are demanding an end to Gaddafi's 41-year rule.

"We're still in that planning and preparing mode should we be called upon to do any of those types of missions, whether humanitarian and otherwise," Lapan told reporters.

Getting food, medicine and other aid into Libya may become critical if order deteriorates faster and more violently.

Secretary of State Hillary Clinton, speaking in Geneva, said there was 'not any pending military action involving U.S. naval vessels' but that they could be used for rescue missions.

MILITARY MIGHT NEARBY

The United States can draw on significant resources in the region as it repositions its forces.

While there are not now any aircraft carriers stationed in the Mediterranean, the USS Enterprise is in the Red Sea and the USS Carl Vinson is in the Arabian Sea.

Across the Mediterranean from Libya, near Naples, Italy, is the headquarters of the U.S. Sixth Fleet, which is responsible for the Mediterranean and parts of the Atlantic.

Its command ship, the USS Mt Whitney, is the only vessel permanently assigned to the area but destroyers and frigates usually operate there as well. On Monday, there were eight vessels in the Sixth Fleet's zone.

U.S. air bases in the region include Aviano, Italy, and Incirlik, Turkey.

Further east, the U.S. Fifth Fleet is based in Bahrain and there are still tens of thousands of U.S. soldiers in Iraq.

The United States could redirect the USS Enterprise but it would take several days to reach Libya, said Andrew Exum, an expert at the Center for a New American Security.

"Much of the commentary has urged President Obama to do something but in terms of military intervention, most of the courses of action, from establishing a no-fly zone to direct action on behalf of the rebels, is a lot harder and riskier than most people understand," he said.

Washington may also be keen to let other NATO nations take the lead on Libya, located on Europe's doorstep.

Susan Rice, the U.S. ambassador to the United Nations, said on Monday that Washington is in talks with its NATO partners and other allies about military options for dealing with Libya.

The Obama administration has signaled that all options are on the table but the movement of forces appears - for the moment - to be a flexing of U.S. muscle rather than a prelude to imminent air strikes or ground operations.

"Washington will want to send a clear signal to the Gaddafi family it is planning toward a post-Gaddafi Libya," Exum said.

"Any U.S. intervention, direct or indirect, will be meant to hasten the departure of the Gaddafi regime."