Though Turkey continues to reiterate its displeasure, it is unclear there is much they can do about Kurdish expansion in Syria, as embedded USA troops are making a direct Turkish attack likely much too risky to contemplate.
Russian Federation has signed an agreement with the Kurdish People's Protection Units (YPG) to set up a military base in northwestern Syria and train the forces in the war-ravaged country.
Though the YPG is allied with both the US and Russian Federation against the Islamic State group, Turkey considers the YPG an arm of the Kurdistan Workers Party, which it has labeled a terrorist organization because of its efforts to establish an autonomous Kurdish state.
"This is the first agreement of its kind, although we have had previous cooperation [with the Russians] in Aleppo city", he added.
The group had about 60,000 fighters by the end of 2016, he said, and has already formed 10 new battalions - each comprised of 300 fighters - since the start of this year.
"The presence of the Russian army units in the Janderis district of the Afrin Canton has taken place as a result of an agreement between our forces and the Russian Army", People's Protection Units (YPG) spokesperson Redur Xelil said on Monday.
"There are no plans to deploy new Russian military bases on the territory of Syria", the defence ministry statement read.
The spokesman also said that the YPG aims to expand its fighting force by almost two-thirds to more than 100,000 fighters.
It will also likely anger Russia's ally Turkey. Turkey, with the help of allies within the Free Syrian Army, has been trying to keep the YPG from gaining terrority to create a contiguous Kurdish area along the Syria-Turkey border.
Russian Federation has been bolstering the regime of Bashar Assad since 2015, providing air cover for Syrian troops.
The YPG make up the bulk of the so-called Syrian Democratic Forces (SDF), a US-backed coalition of fighters who have seized swathes of territory from Daesh terrorist group in northern Syria.
More than 400 volunteers joined the militia by 2015, according to The Syrian Observatory For Human Rights.
It maintains neutral relations with the Russian-backed Syrian government and sometimes clashes with Turkish-backed Syrian opposition forces.