BRUSSELS Western powers have plentiful military resources at their disposal if they want to bring Muammar Gaddafi down, but overt action is unlikely unless there is a dramatic worsening of the turmoil in Libya.
Despite calls for a "no-fly zone" to prevent air attacks on civilians and a deeper refugee crisis, Western leaders appear to hope that increasing political pressure, more shows of force and offers of help to rebels will be enough.
The constraints on intervention are not so much military as political, requiring a United Nations mandate that most analysts see as unlikely without a significant deterioration in Libya, where at least 2,000 people are estimated to have died.
Military analysts say it would be relatively straightforward for Washington and its allies to mount operations against Libya with the resources they have in the region.
The Italian port of Naples, 900 km (540 miles) from Tripoli by sea, is home to the U.S. Sixth Fleet, and NATO has an anti-terrorist task force on permanent patrol in the Mediterranean.
While the United States currently has no aircraft carrier in the immediate region, it and NATO could use a wide range of air bases in Europe, including in Italy, Cyprus and Malta, as well as another major naval base in Portugal.
NATO also has the theoretical capability of deploying 25,000 ground troops at short notice.
"There is no question of the capability to perform such operations," said Shashank Joshi, of London's Royal United Services Institute, a think tank.
"Compared with say Iraq, we are talking about a very specific area and incredible legions of resources to draw from.
"The Mediterranean is an ideal platform -- the southern plank of Europe essentially serves as a giant aircraft carrier, so in that respect things are reasonably straightforward," he said, adding that Libyan air defenses were fairly poor.
But European and U.S. leaders are in no mood to rush into conflict after their troubled, drawn-out involvements in Afghanistan and Iraq.
"They will be desperate not to place themselves in that situation -- unless not doing so would result in even worse massacres," Joshi said.
Even then, any direct action would be more likely to involve a small group of states rather than the 28-nation NATO alliance, analysts at the NATO Defense College in Rome said.
NATO chief Anders Fogh Rasmussen has said that while he is looking at all options, military intervention, including a no-fly zone, would need U.N. backing.
"Legally speaking there are limits," said Florence Gaub at the NATO Defense College.
"Apart from self-defense, any NATO action has to be mandated by the United Nations ... and the United Nations can only issue such a mandate if Libya becomes a threat to international peace and stability, and that is not the case at this stage.
"We see a lot of bad actions by the government against its people, but it's not ethnic cleansing and it's not genocide."
Douglas Barrie of London's International Institute for Strategic Studies said a no-fly zone carried far less risk to Western forces than a ground intervention, although he added: "It's more achievable, but that doesn't mean it's likely."
Joshi said countries such as Russia, China and India were unlikely to give U.N. backing to a no-fly zone -- which U.S. military says would involve destroying ground defenses, not just deterring flights -- and the most likely near-term scenario was an increase in overt and covert support for anti-Gaddafi groups.
This could involve Western intelligence assistance, including supply of communications equipment and possibly arms.
"At a higher level it could involve reconnaissance flights on the coast, disrupting Gaddafi's communications and relaying information about movement of government forces," he said.
"I would actually be very surprised if there are not foreign intelligence services already active in eastern Libya building bridges with rebel groups."
Also likely were shows of force -- such as a U.S. naval force deciding to sail closer to Libya on Monday.
"You could see a carrier group make a more obvious show of force, or perhaps more overt missions on the coast, using fighter aircraft to make Gaddafi think twice," Joshi said.
However, while developing contingency plans, Western powers were mostly hoping the problem would simply go away, Gaub said.
"Many people in Europe hope for option one -- that Gaddafi in the next few days decides to step down.
"If it gets really bad, you get large scale refugee flows, then Libya becomes a threat to stability and world peace and we have much more room for maneuver ... but there are a lot of hopes that things will play out without people having to intervene."
(Editing by Luke Baker and Andrew Roche)