Although the USA has backed the YPG as one of the most capable forces fighting against the "Islamic State" (IS) militant group, Turkey has dubbed it a terrorist group for its alleged ties to the Kurdistan Workers' Party (PKK), a Kurdish group waging a decades-long insurgency in Turkey.
Turkish military operation into the northern Afrin province of Syria has 'actively begun in the field, ' President Recep Tayyip Erdoğan said on January 20, speaking in the central Anatolian province of Kütahya.
At a news briefing, US State Department spokeswoman Heather Nauert saidthe US wanted Turkey to abstain from violence in Afrin.
But the Pentagon said late on Wednesday it does not plan to create an "army" and the force is aimed at fighters from the militant Islamic State (IS) group and maintaining stability in areas recaptured from the jihadists.
Turkey's foreign minister said the Moscow trip by Chief of Staff Hulusi Akar was part of talks with both Russian Federation and Iran, the two main backers of Syrian President Bashar al-Assad, to allow Turkish planes to take part in an Afrin campaign.
Turkish Foreign Minister Mevlut Cavusoglu said that officials were consulting Russian Federation and Iran about the use of airspace for the operation, CNN Turk reported.
"If attacked, we will have no choice but to defend ourselves and our people, but we state in front of the world that we harbor no hostile intent toward Turkey and would only take measures in our own defense in the event of hostile operations against our people", the SDF statement read.
"We will intervene in Afrin", Foreign Minister Mevlut Cavusoglutold broadcaster CNN Turk, adding he did not expect Russian Federation to oppose any operation there.
Turkey had sent its military chief to Moscow on Thursday to seek approval for an air campaign in Afrin, although Damascus warned it could shoot down any Turkish planes in its skies.
"We emphasized that such a step was very wrong", he said.
The US has found the Kurds to be effective allies against the jihadists but Turkey accuses them of carrying out terrorist attacks against Turks.
The Kurdish Democratic Union Party, the political arm of the main Kurdish militia, said that if Turkey begins an operation against Afrin, the world will bear responsibility for the lives of people residing there.
Also on Saturday, Syrian government forces and supporting militias retook a key air base in northwest Syria lost to rebels in 2015.