It prompted condemnations from the Syrian government, Iran and Egypt.
France has called for a UN Security Council meeting later on Monday to discuss developments in flashpoint areas in war-torn Syria, including the Turkish operation. However, those differences do "not mean that [the KNC] will stand behind these violent attacks on civilians", he said. In Turkey's view, the Kurdish fighters that make up a large part of the force are an extension of the PKK - a militant group that Turkey regards as its top threat.
"[The campaign in Afrin] goes to the heart of Erdogan's long-held dream of destroying Kurdish self-determination-not just within Turkey, but in Iraq and Syria as well", she said.
Ankara is now demanding an end to the United States alliance with the YPG, arguing that the fight against IS is over. "We're very much concerned about the ongoing reports of fighting and military operations in the Afrin district", he said.
Heather Nauert, spokeswoman for the US Department of State, said on Sunday that Secretary of State Rex Tillerson spoke with his Turkish and Russian counterparts on the phone and called against an escalation in fighting in northern Syria. But once again, Turkey's other goal has been to check the YPG's westward expansion, and Turkey amassed troops and armored vehicles between Idlib and Afrin.
"They warned us before they launched the aircraft that they were going to do it", Mattis said.
It was the second Turkish town to come under attack.
Turkey said one of its soldiers had been killed.
If Turkey's campaign proves successful, it could continue on to Manbij, where USA -backed Kurdish militants are in control since pushing IS out. "Turkish relationship and Turkey's relationship with North Atlantic Treaty Organisation", said Steven Cook, a senior fellow for Middle East and Africa studies at the Council on Foreign Relations, a nonpartisan think tank.
It is seeking to root out the YPG from its western enclave of Afrin in Syria close to the Turkish border. At least 70 Turkish soldiers were killed, most in battles with IS, which has since been driven from almost all the territory it once held in Syria. They lie outside the control of Syrian President Bashar al-Assad. Damascus said Syrian forces would respond accordingly, including, shooting Turkish warplanes out of the sky.
"It was of course part of the conversation", French Ambassador Francois Delattre said of Afrin after the closed-door talks at United Nations headquarters in NY.
While Washington wants to preserve its relationship with Turkey.it also has ties to Kurdish and other forces forces targeted by Turkey. Numerous militia groups that make up the SDF have been accused of human rights violations and the Turkish government has already said it will attack "nests of terror".