LONDON (Reuters) - Muammar Gaddafi may have lost control of much of his country and military, but a hard core of troops will probably stay loyal as he tries to retain control of western Libya, the coastal strip and the capital Tripoli.
Much of the oil-rich east around Benghazi appears lost. Troops melted away in the face of popular protests inspired by the overthrow of rulers in neighboring Egypt and Tunisia, leaving it in the hands of people's militias and tribal groups.
But so far Gaddafi's opponents appear disparate and disorganized, with no centralized command and little prospect of mounting their own offensives.
That could leave the initiative in Gaddafi's hands.
Analysts say he has always kept the wider military weak and disorganized, leaving real power in the hands of ultra-dedicated units often linked to his own tribal group.
"It's always been kept deliberately nebulous," said Alia Brahimi, head of the North Africa programme at the London School of Economics. "But I think it's clear there are at least several thousand troops -- perhaps more -- who will remain loyal to Gaddafi and it's reasonable to assume that any serious military equipment is likely to be in their hands."
Gaddafi has fomented confusion and rifts in any structure capable of posing a threat, said Jon Marks, a Libya expert and director of the Cross Border Information consultancy.
"It's been divide and rule with the tribes, with political groups, with the regions, and above all with security," he said.
Gaddafi may also be relying on foreign fighters brought in from elsewhere in Africa. In Benghazi, local people told Reuters they had captured several and were holding them in prison.
The Paris-based International Federation for Human Rights, citing reports from Libya exile groups, estimated there were up to 6,000 mercenaries, 3,000 in Tripoli and the rest across the country. Others suggest those numbers may be vastly exaggerated.
There is little solid information on Gaddafi's weaponry and equipment, dented by years of sanctions.
"It is mainly vintage 1950s, 60s and 70s kit," IHS Jane's Middle East analyst David Hartwell said. "Some tanks and armoured personnel carriers and artillery. Basic stuff, but certainly lethal."
The opposition may also have some tanks and heavy weapons from units that defected, he said, but less in the way of spares and ammunition, less idea how to use it and currently no command and control structure.
That may change if defecting military commanders and tribal chiefs form new alliances.Some experts say army chief General Abu Bakr Younus Jaber, a comrade of Gaddafi in the 1969 coup that brought him to power, is believed to have sided with the rebels.
Mansour El-Kikhia, an expert on Libyan politics, estimated Gaddafi can call on 10,000-12,000 Libyan troops, split broadly between a 32nd Brigade led by his son Khamees, and a presidential guard that has been led by another son, Muatassim.
There are also armed members of his revolutionary committees, hardline political structures that enforce internal security and which are likely to stay loyal, if only from a sense of self-preservation.
"Since the 1970s he has drummed into them that their fate is tied to his," Kikhia said.
"For the past 40 years he has delegated the carrying out of many of the atrocities of the regime to these forces, deliberately to implicate them. He has made sure they understood that they live or die with him."
Information from Libya remains sketchy at best, but the battle lines are slowly emerging of what increasingly looks like a Libyan civil war.
Gaddafi appears largely in control of Tripoli, after crushing protests there, while his opponents, though disorganised, have ousted him from the second city of Benghazi.
The situation along the coastal strip between the two cities is more confused. Gaddafi's home town Sirte lies in the middle, apparently under government control.
Fighting was reported in the port city of Misrata, 200 km east of Tripoli. In other coastal towns, military forces have apparently been deployed to quell protesters.
Gaddafi seems to be trying to cement his control of western Libya, but analysts warned he was still far from safe in Tripoli where popular protests remain a potential threat.
Analysts said the air force is the only way he can hit back at opposition targets around Benghazi -- potentially including valuable oil installations. That could be complicated by the arrival of a British frigate to evacuate foreign nationals.
On paper, his air force includes dozens of aircraft, mainly Russian-built jets with some 25 French-made Mirages at the start of the week. But many are believed to be out of service and Libyan pilots have proved reluctant to strike opposition areas.
Two Mirage pilots defected to Malta earlier in the week and a Libyan newspaper said the crew of a third aircraft bailed out rather than bomb Benghazi. Gaddafi is said to have hired foreign mercenary pilots in the past, but finding new crews may be hard.
Any war will likely be low-tech and bloody, analysts say.
The good news is that Libya is believed to have given up and destroyed all stockpiles of chemical weapons as part of its rapprochement with the West.Gaddafi must know that if he did use any such weapons against civilian targets, he would invite an overwhelming response from abroad.
Unlike the World War Two tank battles in the north African desert, fighting in the current conflict is expected to take place in the towns. "This will be urban," said one ex-military security expert now advising the oil sector. "Just like Iraq."
A lengthy Iraq-style conflict or descent into Somalia-style anarchy could provide fertile ground for Islamist radicals at a time of great change in Libya's coastal neighbours.
"The consequences could be very bleak," said LSE's Brahimi. "But right now there doesn't seem to be any appetite in the outside world to do anything to stop it."
Additional reporting by William Maclean; editing Tim Pearce