* Coalition leaders signal resolve for long war
* West seeks regime implosion
* Neither side thinks it will lose
By William Maclean
LONDON, April 15 (Reuters) - Western powers spearheading air strikes against Libya have vowed to oust Muammar Gaddafi come what may, but it is far from clear the wider coalition can stomach a long war or even that his rule is under mortal threat.
A joint article by leaders of the United States, France and Britain on Friday said they would strike loyalist forces until Gaddafi quits, lending support to a widely held view that the time for peace talks is not yet and more bloodshed lies ahead.
"They are digging in for a long conflict," said Firas Abi Ali, senior forecaster for the Middle East and North Africa at Exclusive Analysis.
"They are saying (to Gaddafi) 'We can play the long game as well'," said Alex Warren of Frontier, a Middle East and North Africa research firm.
"These three countries don't want dialogue yet. They are trying to play for time to encourage an internal collapse in Tripoli by defections or by an internal coup."
The message published in three leading newspapers by U.S. President Barack Obama, French President Nicolas Sarkozy and British Prime Minister David Cameron appeared intended to boost the morale of the militarily fragile rebels and send an intimidating message of resolve to close aides of Gaddafi.
A mention in the article of The Hague war crimes court also appeared to be a veiled threat to pursue cases against any Gaddafi aides with blood on their hands who decide to stay loyal.
But Gaddafi, for one, was giving no sign this week that his morale was under a cloud.
Libyan state television on Thursday broadcast footage of the veteran leader, ever the showman, driving around Tripoli in an open-top vehicle. The broadcaster said he went on the outing while the Libyan capital was being bombed by NATO.
His daughter Aisha told a rally in the capital that demanding his removal was an insult.
"Gaddafi isn't even considering departing," said Abi Ali.
It is not only Gaddafi loyalists coalition leaders have to convince of the wisdom of their goals. It is their own allies.
British Foreign Secretary William Hague said on Friday Britain had made progress in persuading other countries to supply more strike aircraft for NATO operations in Libya.
But Italian Defence Minister Ignazio La Russa said Italy would not order its aircraft taking part in operations over Libya to open fire, despite pressure from Britain and France.
France and Britain, the NATO hawks on Libya, have led the air campaign but are growing impatient with lack of commitment and provision of ground strike aircraft from other members.
Friday's article restated, in more forceful terms, an April 13 statement by a much larger group of coalition countries meeting in Qatar that called for Gaddafi to step aside.
But the fact that the leaders of only France, Britain and the United States put their names to Friday's commentary seemed to underline an impression of disarray in coalition ranks.
Exclusive Analysis's Abi Ali said he expected that Libya was facing another six months of stalemate at the very least.
Jon Marks, chairman of UK political risk consultancy Cross-border Information, agreed that the standoff in Libya had the makings of a lengthy conflict.
"The situation in Misrata and Ajdabiya is terrible, as it is in the Berber towns of the Jebel Nefousa where there are signs of an ethnic cleansing policy at work, but otherwise the fighting broadly around the country is actually at a low level, to judge by the casualty figures and the extent that people are travelling around."
"In this context, the standoff looks like it could go on for a painfully protracted period."
An African mission failed last week to secure a ceasefire after Gaddafi's forces continued to shell a besieged city and the rebels rejected any deal not including Gaddafi's removal.
Richard Dalton, a former British ambassador to Libya, said the West hoped that over time the rebel-held east would grow stronger and Gaddafi-controlled parts of the west would grow weaker, prompting at some point a renewed popular uprising against him.
"But for now, neither side thinks it is going to lose: No mediator has an earthly chance in such circumstances," he said.
Others have disagreed.
In an article on British policy, analyst Shashank Joshi of the Royal United Services Institute argued that Britain's insistence on Gaddafi's ousting was a mistake and Gaddafi family members should be allowed to take part in an interim government.
"Goals must be commensurate with (limited) resources and resolve," he wrote. "The objective ought to be regime modification rather than regime destruction. Unless we wish to invite a horrific siege of Tripoli..."
For now there is little sign this argument holds sway.
Asked by Reuters whether there were any moves afoot to encourage talks between one of Gaddafi's sons and the rebel interim National Council, Hague replied:
"I'm not aware of any new effort in that regard ... We do not have the basis yet for a political process to take place." (Additional reporting by Adrian Croft)
Editing by Giles Elgood