Istanbul - Syria’s civil war may be drawing to a close, but the potential for new spasms of violence is bubbling as regional and international actors rethink longstanding strategies.

President Donald Trump’s decision to withdraw US troops has fanned much of the ferment. While it would leave the field to Syrian leader Bashar Al Assad’s Russian and Iranian allies, it has also emboldened Israel to advertise that it’s pummeling Iranian positions, practically taunting Tehran to respond. Some analysts warn of a confrontation between them that could spark a regional war also drawing in Lebanon and Iraq.

At the same time, extremists have staged a mini-resurgence. They’ve targeted US and Kurdish forces, and scored a surprise battleground victory in the last opposition bastion of Idlib, perhaps precipitating an offensive by Damascus and Russia. Meanwhile, a threatened Turkish onslaught could drive Syrian Kurds to seek support from Al Assad and his international partners.

“We should not deceive ourselves and say that the war is over,” Fawaz Gerges, professional of international relations at the London School of Economics, said. “The major battles are over. But the reality is that the strategic and political struggle over Syria by the pivotal regional powers” is intensifying and escalating, he said. “In fact, my take is that this is the most dangerous phase in the Syrian conflict.”

Here are the developments to watch:

The Israeli regime

Israel has long vowed not to let Iran establish a forward base in Syria from where it could attack the Zionist state. But in a major about-face, it’s now openly discussing its operations there after years of silence or vague acknowledgements.

The planned US withdrawal means Israel could lose the strongest bulwark against Iranian forces and proxies in the region - but it’s also happening at a time when Iran has been weakened by US sanctions.

Departing military chief Gadi Eisenkot told the New York Times that thousands of Iranian targets have been struck inside Syria over the past two years, and Israel’s operations have the Trump administration’s blessing. “We strongly support Israel’s efforts to stop Tehran from turning Syria into the next Lebanon,” Secretary of State Mike Pompeo said in a speech in Cairo this month. That was a reference to the political and military power wielded in Lebanon by the Iranian-backed Hezbollah group, a leading enemy of Israel.

The stakes couldn’t be higher. It isn’t in Iran’s interest at this particular moment to give Israel a justification for all-out war, but war “comes sometimes because of a miscalculation, because of unknown variables, because of a black swan, because of a trigger,” Gerges said. The biggest threat in Syria “is an Israeli-Iranian war that could easily escalate into all-out regional conflict.”

Idlib

Moscow and Ankara agreed in September to avert a threatened Syrian regime offensive on the rebel bastion of Idlib, which could have propelled another wave of refugees into Turkey, where nearly 4 million have already taken sanctuary. But the calculus changed last month after Al Qaida-linked fighters swept in and wrested the town from opposition forces backed by Turkey.

Turkish Foreign Minister Mevlut Cavusoglu has signalled his country might agree to a limited Russian-backed Syrian offensive to retake Idlib. That would be a major policy reversal for Ankara, which has backed Syrian opposition forces throughout the war. Having bet on a quick demise of the Syrian regime, Turkey’s bargaining power is limited, and it seems the best President Recep Tayyip Erdogan could do is lobby Russian President Vladimir Putin to take Turkish interests into account.

Russian Foreign Minister Sergie Lavrov “has said Russia would ‘consider’ Turkish interests, but that sounds more like a diplomatic expression for ‘no way’,” said Heiko Wimmen, the Syria, Lebanon and Iraq project director at International Crisis Group in Beirut. “I can’t see why the Russians would want even more Syrian territory under Turkish control.”

Exrtremists

Trump announced in December that US troops would quit Syria because Daesh had been vanquished, but the extremist group has sent deadly signals that it remains a lurking danger. For the second time in less than a week, its suicide bombers targeted US forces on January 21, causing no American casualties but killing five allied Kurdish fighters. The previous week, four Americans were killed and three were wounded when a suicide bomber targeted a patrol in the deadliest attack against US forces in Syria.

Although the extremist group has been largely quelled in Syria and neighbouring Iraq, an American withdrawal while instability still reigns could give it a chance to regroup and even spawn other outfits. That’s what its forerunner Al Qaida did after the US invaded Afghanistan to destroy its hideouts following the attacks of September 11, 2001.

“As Daesh can no longer rely on a formal standing army, it has increasingly resorted to guerrilla tactics and single terrorist attacks,” said Anthony Skinner, a director at UK-based forecasting company Verisk Maplecroft. “The UN and Pentagon suggest it still has as many as 20,000 to 30,000 members in Syria and Iraq.”

Kurds

Trump’s surprise pullout announcement dismayed those who saw it as an invitation to Iran to fill the vacuum in northeast Syria and a betrayal of Kurdish allies who had fought against Daesh. But it was welcomed in Turkey. The presence of US forces has deterred Ankara from attacking the US-backed Kurdish forces, which it regards as linked to Kurdish separatists battling for autonomy in southeast Turkey.

It’s not clear Russia would approve a Turkish operation deep into Syrian territory. Conflicting voices from Washington on the pullout’s timetable has held the Turkish military at bay, but Erdogan has said Turkey would take over the Kurdish-controlled town of Manbij in Syria’s north and eventually hand it over to “its real owners.”

The Kurdish YPG militia, alarmed by the prospect of a US pullout, has been urging the Al Assad regime and Moscow to send troops to border areas Kurdish forces have held for years to hold off any Turkish offensive. A Turkish campaign in the northeastern city of Afrin drove out Kurdish forces and civilians last year.

Erdogan could please nationalists ahead of municipal elections in March with an attack on Kurdish militants but the possible economic fallout from increased tensions with the US weakens “the dividends” of such an operation, according to Skinner.

“What has been consistently clear is that the YPG is Turkey’s top priority,” Skinner said. But “Turkey would clearly prefer to avoid launching a military incursion into territory where US forces are still present.”

It’s difficult to imagine that Turkey will invade without Moscow’s consent, and the Syrian regime won’t move “unless it can be sure that the US will not still mow them down from the air,” Wimmen at the International Crisis Group said.

“I believe that Washington really wants to avoid the impression that Iran and its allies step into the void created by the withdrawal, and allowing the regime to enter the area would do just that,” he said. “Perhaps the Kurds can reach a deal with the regime, but Damascus has been intransigent in the past and has even less reason to be flexible now.”