Renewed clashes between Kurdish and Turkish forces have tested a shaky cease-fire in northern Syria, as the Russia-backed Syrian government moved troops into the area in part of its efforts to reclaim territory it ceded during the eight-year war.
US Defense Secretary Mark Esper, meanwhile, said the US would reinforce its defence of oil fields in northeastern Syria, as America shifts away from President Trump's earlier planned full troop withdrawal from the region.
Speaking at a press conference after meetings in Brussels, Mr Esper said the deployments would include some mechanised forces: a classification that includes tanks, artillery, armoured vehicles and other heavy equipment.
The moves are the latest indication that several players are pushing to exert control in northern Syria after the sudden US decision this month to withdraw roughly 1000 troops who supported the Kurds in the fight against IS terror group.
Since then, Russia has consolidated its role as the main powerbroker in the country, while the US has announced several new plans, confusing allies.
The Syrian oil fields are controlled by the Kurds, though there are US troops at several of them.
Maintaining troops at the sites would help preserve some US leverage in the region, giving Washington a foothold to counter Syrian President Bashar al-Assad, as well as Russia, which has contracts for the oil fields.
Following a pact struck between Ankara and Moscow this week, Turkish forces on Wednesday suspended a military campaign against the Kurds - whom Ankara regards as a terrorist threat - giving Kurdish fighters 150 hours to leave a 30-kilometre-deep belt that Turkey calls a safe zone.
Nonetheless, Turkey and its local allies have been conducting a ground assault including artillery shelling on several border villages since Thursday morning, forcing thousands of civilians to flee, the Kurdish-led Syrian Democratic Forces said.
Turkey didn't comment on the claim, but accused the Kurds of targeting its forces. The Turkish presidency's press office said five Turkish soldiers were injured on Thursday.
The agreement between Russia and Turkey divides up oversight over the border area between the two countries.
As Russia is a key backer of Mr Assad's regime, the US pullout could allow government forces to reconstitute in some areas currently under control of the Kurds, who are seeking protection after the exit of the US.
Up to 1300 Syrian government forces and at least 160 vehicles arrived Thursday to the area around the town of Kobani, located on the Turkish border, according to the Rojava Information Center, a media activist network.
Turkish drones attacked southeast of the border town of Ras al-Ain on Thursday and Friday, killing at least one SDF fighter, according to David Eubank, a US humanitarian worker volunteering with the Kurdish-led forces.
A US Air Force F-16C Falcon fighter about to take off from Incirlik air base in Turkey. There are concerns about the nuclear weapons stored at the base.
"These Turkish airstrikes have not stopped any day during this so-called ceasefire. Along with the Free Syrian Army, they attacked all day yesterday from noon until night," Mr Eubank said, referring to Turkish-backed Syrian rebels.
Eight Turkish-backed troops and three SDF fighters were killed Friday, said the Syrian Observatory for Human Rights, an independent monitoring group. Three nurses working with an ambulance team were killed by Turkish-backed rebels, and their bodies discovered in a water sewage system on Thursday, the Kurdish Red Crescent said.
Under the Turkey-Russia agreement, Russian and Syrian security forces would oversee the withdrawal of Kurdish fighters, some of whom have already started to leave, from the safe zone and conduct joint patrols in parts of the area.
On Friday, the Russian defence ministry said it has sent around 300 more military police officers from Chechnya to the Syrian-Turkish border area.
