By Tom Perry
BEIRUT (Reuters) - President Bashar al-Assad's path to a final victory in the war in Syria is strewn with diplomatic landmines that will complicate his attempt to recover "every inch" of the country and may leave big areas out of his grasp indefinitely.
Assad's advances have accelerated this year in the conflict that began in 2011. Russian and Iranian military power helped deliver the defeat of the last rebels near the capital Damascus and the city of Homs, and allowed him to recover the southwest in a matter of weeks.
Rebels who once reduced Assad's control to a small fraction of Syria now pose no military threat to his rule. With his allies' help, Assad controls the bulk of the country and is inviting investors from "friendly" nations to help rebuild it.
Declaring the return of "normal life", his Russian allies are urging refugees to come home, saying there is nothing to fear from Assad's government, though many people continue to flee areas that are falling back under its control.
But some are trickling back and Moscow is seeking international support for them, in the apparent hope that Western states that backed the opposition will now direct aid to government-held areas, spreading the burden.
But with Russia in the ascendancy, there is no sign of the kind of negotiated political transition which the West has said is needed to unlock its support and to encourage the bulk of the millions of refugees in Europe and the Middle East to return.
Assad has recovered the frontiers with Jordan and the Israeli-occupied Golan Heights, and says he will press ahead.
Almost all of northern Syria and much of the east remain outside his grasp. But in these areas a new test awaits: hostile Turkish and U.S. forces that have carved out separate spheres of control on Syrian territory.
Russian priorities, particularly its ties with Turkey, may largely determine how the war unfolds from here.
So too will U.S. President Donald Trump, who has given conflicting signals over how long American forces will maintain their foothold across a swathe of the east and northeast. U.S.-backed Kurds, wary of their unpredictable ally, are beating a path to talks with Assad, seeking to safeguard their autonomy.
"The conflict is entering a new phase. But it is hard to say the war is ending when so much of the country still remains outside the government's hands," said Noah Bonsey, the International Crisis Group’s Senior Analyst on Syria.
"And it is still unclear to what extent an insurgency might emerge in parts of Syria that the government controls."
Islamic State militants killed more than 200 people in the government-held Sweida region last week. The war is estimated to have killed hundreds of thousands of people.
Assad has flagged his next target: the rebel-held Idlib province. "Now Idlib is our target, although not only Idlib," Assad told Russian media last week.
A sanctuary for Syrians who have fled government advances in other parts of the country, Idlib is controlled by an array of insurgents who have often fought each other.
Jihadist groups hold sway, and foreign fighters are estimated to number in the thousands, according to the Syrian Observatory for Human Rights, which reports on the war.
Idlib falls within an arc of territory stretching east to the Euphrates River where Turkish forces are deployed.
Turkey has aimed to roll back Kurdish groups which it sees as a national security threat, but also to prevent more Syrians spilling over its border: Turkey already hosts 3.5 million refugees. In agreement with Iran and Russia, it has set up 12 military posts in Idlib and adjoining areas.
The possibility of an Idlib offensive is ringing alarm bells in Turkey. A top U.N. official has warned another 2.5 million people could flee toward the border in the event of an attack.
President Tayyip Erdogan has been pressing Russian President Vladimir Putin to make sure that does not happen.
"Of course, it isn't possible for us to accept any regime attacks directed at Idlib. I discussed this with Putin. We've already agreed on this issue," Erdogan was reported as saying by the Turkish daily Hurriyet.
"I do hope that he would do what's necessary on this."
The pan-Arab Alsharq Alawsat newspaper has reported details of a Turkish proposal to Russia over Idlib that includes the idea that rebels there surrender heavy weapons to the Turkish army. Such proposals - including that rebels be reorganised into a "national army" - are likely to be anathema to Assad.
"If Assad has reiterated one consistent refrain through the years of uprising, it is nationalism. When Assad says he will take back every inch of Syrian soil, we should believe he means it," said Joshua Landis, an expert on Syria and head of the Center for Middle East Studies at the University of Oklahoma.
Despite this, a source in the regional alliance that fights in support of Assad thought an imminent Idlib assault unlikely.
"The Turkish side will continue to hold on tight because the cards are in its hands," the source said. "Military action will happen after the deck is shuffled and the Turkish-Russian-Iranian agreement for that region is finished."
Some rebels, doubtful of Russia's commitments, fear the worst. "We are preparing for any escalation, and carrying out reinforcement operations and redeploying forces in preparation for a battle in the near future," Colonel Mustafa Bakour, a commander in the Jaish al-Ezza Free Syrian Army faction, told Reuters in a message from northern Hama province.
"We expect a Russian military escalation."
An Idlib offensive could prove more difficult than previous government campaigns. The jihadists who hold sway in the province have proved to be some of the toughest in the war.
"An offensive may drive groups that are currently focussed on maintaining territory in Idlib into the kind of guerrilla insurgency that some in the jihadist movement have been encouraging them to adopt for years," Bonsey said.
(Additional reporting by Laila Bassam in Beirut, Tulay Karadeniz in Ankara and Suleiman al-Khalidi in Amman, Editing by Timothy Heritage)