By Ross Colvin
WASHINGTON (Reuters) - The United States is reluctant to get sucked into Libya's increasingly messy conflict, despite its fears that the oil-producing North African country is descending into chaos.
WHAT COULD TRIGGER U.S. MILITARY INTERVENTION?
Possibly a major jump in the death toll. Analysts say massacres of civilians, aerial bombing of civilian targets or a concerted military offensive by Libyan leader Muammar Gaddafi to retake rebel-held territory could be possible triggers.
While the Obama administration is sensitive to criticism that it has been slow to respond more forcefully to Gaddafi's bloody crackdown on opponents, it has made clear it will not be rushed into making any hasty decisions.
Media reports of aerial bombing of civilians have helped drive calls for international military intervention but Defense Secretary Robert Gates and Admiral Mike Mullen, the chairman of the Joint Chiefs of Staff, said on Tuesday the United States has so far been unable to confirm them.
Two U.S. amphibious assault ships are now sailing toward Libya but U.S. officials have stressed they are being sent to help with possible humanitarian efforts. Marines on board could be used to help protect any international aid mission.
For now, the United States appears to be content with symbolic shows of military strength and seizing a record $30 billion in Libyan assets.
COULD THE U.S. TAKE UNILATERAL MILITARY ACTION?
U.S. officials have all but ruled that out. The Obama administration has repeatedly stressed it is working with NATO member states and the United Nations Security Council.
There is no Security Council resolution authorizing the use of armed force and there is no agreement within NATO for military intervention, Gates said.
With 47,000 U.S. troops still in Iraq and some 100,000 in Afghanistan, the Obama administration has no desire to become embroiled in yet another costly war that would only fuel anti-American sentiment in the Arab world. Arab states have already warned against foreign intervention in Libya.
Gates, who has spearheaded a drive to cut the military budget to help cut a record U.S. deficit, said moving additional U.S. forces closer to Libya could have consequences for the war in Afghanistan.
WHAT FORM COULD INTERVENTION TAKE?
No one is talking about putting U.S. troops on the ground but there have been widespread calls for a "no-fly" zone to be imposed to prevent Gaddafi from using warplanes or attack helicopters to strafe rebels on the ground.
Secretary of State Hillary Clinton has said the United States and its NATO allies are actively considering such a step but the Pentagon has been cool to the idea, highlighting the many challenges of enforcing a no-fly zone.
Air strikes would be needed first to destroy Libya's anti-aircraft defenses, Gates pointed out on Wednesday.
"Let's just call a spade a spade," he bluntly told lawmakers. "A no-fly zone begins with an attack on Libya to destroy the air defenses ... and then you can fly planes around the country and not worry about our guys being shot down."
Analysts question the effectiveness of a no-fly zone since Gaddafi appears to be relying mainly on ground forces. Enforcing the ban would also require hundreds of aircraft.
A rebel group in east Libya calling itself the National Libyan Council wants U.N.-backed air strikes on foreign mercenaries reportedly being used by Gaddafi.
But the United States will be wary of such calls as it is still trying to identify who's who in the mishmash of opposition groups taking part in the revolt against Gaddafi.
It says there are no immediate plans to arm the rebel groups, who already appear to be relatively well equipped with weapons seized from military arms depots or defecting soldiers, including tanks and anti-aircraft weapons.
WHAT ARE THE OBSTACLES TO INTERVENTION?
While setting up a no-fly zone may sound like an attractive option because of the limited potential for casualties, what happens if fails to halt Gaddafi's attacks?
"If that doesn't work, are you then going to send in the Marines?" said Bruce Riedel, a former senior Middle expert at the CIA who has advised President Barack Obama on the war in Afghanistan.
The popular protests against Gaddafi's rule appear to have evolved into a near civil war that has already cost the Libyan leader great swaths of his country. Helping unarmed protesters is one thing, taking sides in a civil war quite another.
The U.N. Security Council also appears unlikely to authorize the use of force. Veto-wielding member China has already expressed misgivings about a no-fly zone.
WHAT IS WASHINGTON DOING ON HUMANITARIAN AID?
The development agency USAID has sent advance teams to the Egyptian and Tunisian borders with Libya to help figure out what is needed for the tens of thousands of refugees reported to be fleeing.
They are also conducting emergency reviews of regional food and medicine stockpiles.
The amphibious assault ships USS Kearsarge and USS Ponce, which are laden with food, water-making equipment and shelters, are due to arrive off the Libyan coast in a "couple of days," Chief of Naval Operations Admiral Gary Roughead said.
(Additional reporting by Missy Ryan, Andrea Shalal-Esa, Mark Hosenball and Andrew Quinn; Editing by John O'Callaghan and Cynthia Osterman)