President Tayyip Erdogan has signalled a Turkish military operation in a Kurdish-controlled territory of northern Syria is imminent, despite US warnings that a unilateral intervention would be "unacceptable".
Washington and Ankara held last-ditch talks this week to set up a "safe zone" in northern Syria. They agreed on Wednesday to establish a joint operation centre in Turkey to manage the zone, but neither said if they had overcome two main points of division: how far the zone should extend and who would command forces patrolling it.
The US, which armed Kurdish YPG militia and backed them in the fight against the so-called Islamic State group (IS) in Syria, wants to protect its military partners. It had so far resisted Turkey's demands for full control of a long strip of land that would extend 32km into Syria.
Turkey has undertaken two previous military operations in northern Syria in the past three years.
Here we unpick why is Turkey threatening to make new incursions in northern Syria? What are the implications for Syrian Kurds, the fight against IS, and already strained US-Turkish relations?
Why would Turkey carry out a military operation in northern Syria?
Ankara views the Kurdish YPG militia, which plays a leading role in the Syrian Democratic Forces that hold sway over hundreds of kilometres of Syria's northeast border region, as terrorists who pose a grave security threat to Turkey.
"Turkey will do everything in its power to prevent the emergence of a Kurdish entity along its border," Adel Bakawan told Euronews. A Kurdistan specialist, Bakawan is the director of the Iraq Centre of Sociology and an Associate Researcher at the French Institute of International Relations.
Turkey is also trying to secure its role in tomorrow's Syria amid a power struggle between various players, Bakawan said, which range from Washington, Moscow and Teheran to militant Islamist groups and Kurdish militias. From this perspective, Ankara's strategic interest is to control as much territory as possible.
Another reason behind the military operation might found in domestic politics. "Erdogan's party AKP is deeply divided following the loss of major cities such as Istanbul and Ankara during local elections earlier this year," Bakawan said. "A military intervention would allow the embattled Turkish leader to take centre-stage once again."
How could military intervention affect US-Turkish relations?
A Turkish intervention in northern Syria would likely have disastrous consequences on already strained relations between the two NATO allies.
Turkey angered the United States last month by buying Russian missile defence equipment. The two countries are also split over Washington's sanctions on Iran and the US' refusal to extradite a Muslim cleric wanted by Ankara.
According to experts, potential military targets for a new Turkish intervention in northern Syria could include the areas of Manbij, Tel Abyad or Kobane. US forces operate to varying degrees in all three areas, meaning American troops could risk being caught up in any hostilities.
US Defense Secretary Mark Esper said on Tuesday any Turkish operation in northern Syria would be "unacceptable" and the United States would prevent unilateral incursions.
But the US may feel torn between their century-long alliance with Ankara on one hand and their strategic partnership with Syrian Kurds on the other. The latter is key in the fight against IS and in securing Washington's role in post-war Syria, Bakawan said.
The researcher noted that Washington's attempt to please both sides led to contradictory statements over the past few weeks and that the world superpower "still lacked a stable, clear and fixed policy" on the matter.
What are the implications for Syria's Kurds?
"Syria's Kurds have been in a bad situation since January 2019, when they lost Afrin," Bakawan told Euronews. Last year, Turkish troops and their Syrian proxies overran the northwestern Kurdish enclave after months of heavy bombardment.
"If the US gives up to Erdogan this time, negotiations with Bashar al-Assad might be an option for the Kurds," Bakawan said. But considering the Syrian president's views, this would mean the end of the Kurds as a political entity, the researcher added, even though they could exist as a cultural group within the Syrian state.
Another option would be to convince Moscow and Tehran, which have been active players in the Syrian war, to grant autonomy to the Kurds and plead their cause to Damascus and Ankara, Bakawan said.
The fact that Kurdish forces control prisons where some 10,000 IS fighters are detained is likely to give them leverage. If the Kurds decide to open the prisons and let fighter out, it would be "total chaos," Bakawan said.
Will a Turkish operation undermine the fight against IS?
In a new report published on Tuesday, the US Pentagon warned the IS group was "re-surging in Syria," just as Washington has been reducing troops since the so-called caliphate was defeated.
"Ideologically and socially, the IS group is still present in Syria even if it was defeated militarily," Bakawan said.
Kurdish forces have warned their engagement against a Turkish operation would mobilize all their resources. They have also suggested they would not be able to guarantee that IS prisoners currently under their custody would remain under control.
A Turkish intervention carries the risk of a "spectacular" military comeback from IS, Bakawan said.