Beirut: Russia is setting up a military base in northwestern Syria in agreement with the Syrian Kurdish YPG militia that controls the area and will be training YPG fighters as part of the fight against terrorism, the militia's spokesman said on Monday.
YPG spokesman Redur Xelil told Reuters the agreement with Russia was concluded on Sunday, and that Russian troops had already arrived at the position in the northwestern region of Afrin with troop carriers and armoured vehicles.
The move will likely anger neighbouring Turkey. Ankara views the YPG as an extension of the Kurdistan Workers' Party (PKK), which is waging an insurgency inside Turkey.
"The Russian presence... comes in agreement between (the YPG) and the Russian forces operating in Syria in the framework of cooperation against terrorism and to help train our forces on modern warfare and to build a direct point of contact with Russian forces," Xelil said in a written statement.
"It is the first (agreement) of its kind," he added.
Turkey has launched a cross-border offensive along a section of the Turkish-Syrian frontier to prevent further gains by the YPG, which controls swathes of northeastern Syria and the Afrin pocket of northwestern Syria.
The YPG is also allied to the United States in the fight against Islamic State in Syria, and is playing a major part in the U.S.-backed offensive against IS's urban stronghold of Raqqa, further east.
"The agreement came into force today," Xelil said, declining to say how many Russian troops had arrived in Jandaris, the place where the base is being established.
Jandaris has previously been shelled by Turkish forces from across the nearby frontier, Xelil added.
Meanwhile, Syria's army staged a counterattack in northeastern Damascus on Monday, but there were conflicting accounts of how much ground it regained after Sunday's rebel assault.
A Syrian military source and a war monitor said the army had recaptured all the positions it had lost, but rebels said they were still holding on to some of their gains despite heavy aerial bombing that had forced them to retreat.
The army's advance involved heavy fighting and intense air strikes, the Syrian Observatory for Human Rights and a military media unit run by the army's ally Hezbollah said.
A Reuters witness saw war planes circling in the sky above northeast Damascus, mortar fire, and a street with a line of burned-out cars from the fighting in the Jobar and Al Qaboun districts.
The Observatory, a British-based war monitor that collects information from a network of sources across Syria, said heavy fighting continued and that the army had unleashed more than 500 air raids and artillery strikes. The Hezbollah-run military media unit said that air raids were aimed at rebel supply lines.
Rebels had attacked in Jobar to relieve military pressure after their loss of ground in nearby Qaboun and Barza, a commander from the Failaq Al Rahman group which is fighting there said on Sunday.
The intensity of the Syrian army's counterattack forced the rebels to retreat on Sunday night from at least 60 per cent of the areas they captured that day in an industrial area that separated Qaboun from Jobar, a rebel spokesman said.
"Today the clashes are difficult and there is no progress in the face of this ferocious bombardment that is not just limited to the frontline but all night the regime was shelling the cities and towns in Eastern Ghouta in retaliation," Wael Alwan, the spokesman for Failaq Al Rahman, told Reuters.
Syrian President Bashar Al Assad and his army, along with allied Russian, militia forces, have put rebels on the back foot with a steady succession of military victories over the past 18 months, including around Damascus.
For rebels, however, their first such large scale foray in over four years inside the capital signalled they were still able to wage offensive actions despite their string of defeats.
"This battle gave hope we can stand up to the regime's military machine... It was again us going back to a sort of balance of force and not just defending ourselves," Alwan said.
Rebels still hold a large, heavily populated enclave in the Eastern Ghouta district of farms and towns to the east of the capital, as well as some Damascus districts in the south, east and northeast of the city.
The most recent fighting has focused on the areas around Qaboun and Barza, which the army has isolated from the rest of the main rebel enclave of Eastern Ghouta and the eastern districts of Damascus.