(Reuters) - Six years since the start of the uprising against President Bashar al-Assad, he is winning on the battlefield but Syria’s civil war is far from over, with his once stable country broken into fiefdoms ruled by rebels and warlords.

FILE PHOTO: Syria's President Bashar al-Assad speaks during an interview with Yahoo News in this handout picture provided by SANA on February 10, 2017, Syria. SANA/Handout/File via REUTERS

While few non-partisan observers think the conflict will end soon, fewer still believe Assad can retake the whole country. But since all outside players now seem to have adjusted to his staying, no one expects a peace deal either.

Many foresee, at best, a ceasefire observed much of the time over much of a territory that will be effectively partitioned between competing forces.

During five years of stuttering negotiations between the government and the opposition, brokered by the United Nations, the United States and Russia, and more recently by Russia and Turkey, the sticking point has been whether Assad would go. Now, the starting point is that he will stay.

“We have to be realistic – he’s not leaving”, says Robert Ford, a former American ambassador to Damascus who resigned in frustration at President Barack Obama’s indecision on Syria and remains in contact with many of the conflict’s protagonists.

“After Aleppo, there is no chance” of dislodging Assad, Ford added. “That’s the result of the military victory they won.”

It started six years ago with protests across Syria, mainly among the country’s majority Sunni Muslims, against Assad and his family’s 40-year rule built around the minority Alawite community, an offshoot of Shi’ite Islam.

In March 2011, “Arab Spring” protests sweeping the region had already dislodged autocrats in Tunisia and Egypt, and would later claim the long-term rulers of Libya and Yemen, two other countries still embroiled in civil wars six years on.

Assad responded to Syria’s protests with unconstrained violence, turning the uprising into a war to the death.

Western leaders including Obama predicted Assad would quickly fall. But he hung on, using the resources of the state and backing from Iran and Lebanon’s Hezbollah Shi’ite militia to fight rebels funded by Arab states to a stalemate. A year and a half ago, Russia joined the war on his side, tipping the balance in his favor.

Today an estimated half a million people have been killed, half the population has been uprooted in the world’s biggest refugee crisis, and the war has set new standards of savagery in its impact on civilians.

Most of the world’s major powers and regional states have backed proxy forces in a complicated multi-sided conflict, while the Islamic State jihadist group, at war with everyone else, declared a caliphate straddling the border with Iraq.

Anti-Assad rebels, split between nationalists and Islamists, are splintered and abandoned by their half-hearted patrons. International actors - Russia, Iran, the United States and Turkey - crowd an ever more confusing battlefield.

And Assad is still there, proclaiming he will reconquer every inch of a devastated country shattered into ruins.

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RESEMBLING LEBANON AND IRAQ

Since Russia stormed into Syria 18 months ago, Assad has surged from the verge of a collapse among his depleted loyalist forces to a formidable position of military strength.

His recapture in December of the rebel enclave in Aleppo, their last urban stronghold, was a major turning point in the war and left the insurgents bottled up in rural Idlib province and battling each other.

Syria now faces a situation that could resemble neighboring Lebanon at several stages of its 1975-90 civil war, when it was carved into fiefdoms by competing militias, with long lulls in fighting punctuated by violent cataclysms.

It could also share some traits with Iraq after the first Gulf War, which left its former ruler Saddam Hussein in power for more than a decade as a global pariah, with his legitimacy in question and his economy strangled by sanctions.

Andrew Tabler, a Syria specialist at the Washington Institute for Near East Policy think-tank, does not see anyone, much less Assad’s allies Russia or Iran, ordering the president out, although he can still imagine a violent end for Assad.

“I don’t see Russia or Iran asking him to step down, but we do have to prepare for an eventuality in this volatile environment that Assad may be targeted for assassination because of how much of a barrier he is to a settlement - him personally.”

Assad himself, asked in an interview if he had thought about leaving Syria, said: “Never. After six years, the most difficult time has passed, which was in 2012-13. Those times we never thought about (leaving), how could I think about it now?”

For the former ambassador Ford, who once saw Assad’s demise as inevitable, the flip side of him now seeming impregnable is that his opponents can never accept his continued rule.

Among the millions of Syrian refugees and internally displaced, many cannot return to homes in areas they see as subject to the tyranny of rule by Assad’s secret police, which the opposition blames for hundreds of thousands of deaths.

CONVERGING INTERESTS

Nevertheless, an emerging international consensus in practice favors pro-Assad forces, illustrated by events around the northern town of Manbij this month, when Washington sent its first openly acknowledged regular ground troops.

The small U.S. force was sent to separate Kurdish fighters Washington has supported from rival Arab rebels backed by Turkey near the town. By blocking any advance of the rebels, the U.S. move was seen as a tacit endorsement of the presence of Assad’s Russian-backed forces in the area.

“The Americans are cooperating with the Russians in a way that is going to help complete the regime’s victory in Syria,” says Eugene Rogan, professor of modern Middle Eastern history at the University of Oxford, of the U.S. moves in Manbij.

Syria watchers say a patchy ceasefire in place now - brokered by Russia and Turkey - could be consolidated. But they believe Assad will eventually try to annihilate the rebel forces pushed into rural Idlib, one village at a time.

Yet Assad and his patrons will always face the constraint of limited manpower, which stretches his forces ever thinner the more territory he regains and makes his troops more exposed to attacks by opposition groups and jihadis of Islamic State.

Recent deadly attacks inside government-held cities, on a military intelligence headquarters in Homs and on Iraqi Shi’ite pilgrims in Damascus, underline the threat, which Assad’s refusal to compromise could magnify.

“If you’re Iran and Russia and you know Assad’s manpower limitations and political rigidity you have a problem,” says Tabler. “You have to cut a deal so that Iran and Russia don’t have to surge troops into Syria, which is their dilemma.”

Ford, after informal recent discussions with Russian experts familiar with Moscow’s policy, says the Russians believe the Syrian army is exhausted and that it would be difficult for Assad to recapture all of the country.

Since Assad cannot hope to run Syria with the iron centralized control he once exercised, there needs to be decentralization, Ford said, noting that Moscow had proposed a less-centralized constitution but Assad had rejected it.

That leaves the likely outcome continued de facto partition of Syria, even if Assad continues to make incremental gains.

“The only way to avoid partition, without a peace agreement, is for the Syrian government to recapture the whole country and that could take years,” says Ford.

Boundaries are fluid, but at present Assad and his allies will probably keep control of the main population centers, from Aleppo in the north to Deraa in the south, including the coast and the capital, Damascus. Many of the millions of people who fled those areas are unlikely to return soon.

Turkey and a rebel force that it backs hold a pocket in the far north, while other rebels retain their big enclave in Idlib and west of Aleppo. The Syrian Kurds control areas in the northeast and northwest.

The next year will probably see an attempt to push Islamic State from Raqqa, its citadel on the Euphrates river in northeast Syria. The United States seems intent on relying on Kurdish fighters for that assault, to the chagrin of Turkey which views the main Syrian Kurdish force as enemies.

Joshua Landis, director of the Center for Middle East Studies at the University of Oklahoma, said Assad’s continued rule was increasingly - if tacitly - accepted by the forces that have called for his downfall.

But Landis and others conclude that even if the West and Syria’s neighbors accepted Assad’s partial reoccupation of the country, it would not mean the international community would embrace him, much less help pay for Syria’s reconstruction.

“The entire western world hates Assad and they’re going to squeeze him economically,” Landis said. “He’s not going to be reintegrated, he’s going to be like Iraq used to be under Saddam Hussein.”