BEIRUT (AP) — Turkey shelled positions held by the main Kurdish militia in northern Syria for a second day on Sunday, drawing condemnation from the Syrian government, whose forces are advancing against insurgents in the same area under the cover of Russian airstrikes.
Turkish artillery units in the southern province of Kilis fired at Kurdish fighters in the Syrian town of Azaz in Aleppo province, saying it was in response to incoming Kurdish fire, Turkey's state-run Anadolu Agency said.
Turkish troops have shelled areas under the control of Syria's main Kurdish faction, the People's Protection Units, known as YPG, in the past. But Turkey appears increasingly uneasy over the group's recent gains in northern Syria.
"Turkey has responded in this manner in the past," said Yalcin Akdogan, Turkey's deputy prime minister. "What is different is not that Turkey has responded in such a way but the fact that there are different movements in the region. The YPG crossing west of the Euphrates is Turkey's red line."
The YPG is the main fighting force of Syrian Kurds and a key ally of the U.S.-led coalition battling the Islamic State group. Turkey, which is also in the alliance, considers it an affiliate of the Kurdistan Workers' Party, or PKK, which has waged a long insurgency against Turkey.
A coalition of Kurdish-led Syrian fighters known as the Syrian Democratic Forces recently seized a number of villages near Turkey's border. Ankara appears concerned that they could reach the opposition stronghold of Azaz, which is home to a major border crossing that has been controlled by militants since 2012.
Diplomats from a group of countries that have interests in Syria's five-year civil war, including the U.S., Russia, Turkey, Saudi Arabia and Iran, agreed on Friday to seek a temporary "cessation of hostilities" within a week.
But the fighting on the ground — which has sent tens of thousands of people fleeing toward the Turkish border, where they sleep in the open air — has accelerated.
A top Syrian opposition figure, former Prime Minister Riad Hijab, criticized Russia on Sunday for continuing with its bombing in Syria.
"You ask me if I accept a cease-fire or a cessation of hostilities. I ask you 'Why is the onus on the opposition and whether it has preconditions for negotiations?'" Hijab said. "I would like to see a single day of a cessation of hostilities in order to give a chance for real political movement."
He was addressing the Munich Security Conference, an annual gathering of foreign and security policy leaders.
Akdogan said Kurdish gains in northern Syria — facilitated by a Russian-backed government offensive in the same area — are also putting "unacceptable" pressure on opposition-held areas in Aleppo.
The Syrian Observatory for Human Rights, an opposition group that monitors the conflict, said two fighters from a coalition of Kurdish and Arab fighters have been killed and seven others wounded in the shelling.
Also on Sunday, Iran's air defense chief said his country is ready to help defend Syria's airspace, marking the first time Iran has offered to assist with Syrian air defenses.
The semi-official Tasnim news agency quoted Gen. Farzad Esmaili as saying: "We will help Syria in a full-fledged manner if the Syrian government requests help."