ANKARA, Turkey (AP) - Two Turkish soldiers were killed Thursday in an airstrike in northwestern Syria, Turkey said, after an attack by Ankara-backed opposition forces that targeted Syrian government troops. The deaths came after the Turkish president threatened to expand his nation's involvement in Syria if another one of his troops were hurt.
At least 15 Turkish soldiers have been killed in Syria this month amid a crushing offensive by Syrian President Bashar Assad's forces aimed at recapturing remaining opposition-held areas in the region.
Intent on halting the advance, Turkish President Recep Tayyip Erdogan had vowed Feb. 12 to take military action "everywhere in Syria" if another Turkish soldier was killed or wounded.
The multiple front offensive has triggered the biggest single wave of fleeing civilians in Syria's nine-year war, displacing nearly 1 million people who have rushed toward the Turkish border and are sheltering in tents or sleeping rough in harsh winter weather.
It has also risked completely shattering a fragile cooperation between Ankara and Moscow, which back opposing sides of the Syria war. Ankara has sent thousands of soldiers to northwestern Syria to try to stem the Syrian government advance on the province near the Turkish border, leading to the repeated flare-ups.
Thursday's exchange marked a serious escalation that risks growing into a full-blown conflict between Turkey and Syria. Erdogan has also called on Assad's forces to retreat from Idlib or face an "imminent" Turkish attack.
The exchange began after opposition fighters shelled Syrian government forces and entered the village of Nairab, which Assad's forces had captured Feb. 3, the Turkish Anadolu agency said.
The Russian military said the militants' actions "were supported by Turkish artillery fire," which allowed them to break through the Syrian army's defenses. Four Syrian soldiers were wounded in the Turkish shelling, it said.
At the Syrian military's request, Russian Su-24 bombers then struck the militants to prevent them from advancing and allowing Syrian government forces to "successfully repel all attacks," the military added.
It was not immediately clear whether it was the Russian airstrikes that killed the two Turkish soldiers and injured five others.
Fahrettin Altun, a top aide to Erdogan, said the attack was carried out by Syrian government forces. On Twitter, he wrote: "The blood of our martyrs won't be left unaccounted for."
The Turkish Defense Ministry tweeted as many as 50 Syrian government soldiers were killed and that five tanks, two armored personnel carriers and other equipment were destroyed.
In Moscow, Russian Foreign Ministry spokeswoman Maria Zakharova raised what she called "serious concern about the Turkish military support for the militants."
"This incident represents a violation of the Russian-Turkish agreements on separation between the armed opposition and terrorists and the creation of a demilitarized zone. It risks provoking further escalation of the conflict in that part of Syria's territory," she said in a statement.
Turkey and Russia have closely coordinated their moves in recent years in Idlib province. Turkey maintains observation posts in northern Syria that were set up to monitor a 2018 cease-fire agreement with Russia. The truce collapsed in late 2019, leading to the current Syrian offensive, backed by Russia.
Russian officials said they hold Turkey responsible for the collapse of the cease-fire deal, saying Ankara had not held up its end to rein in militants who continued attacking Syrian and Russian targets.
Turkish Defense Minister Hulusi Akar on Thursday rejected the Russian assertion, saying Ankara was making progress against radical groups in Idlib when the Syrian government launched its offensive.
Ankara sent in thousands of additional troops and armored vehicles in recent weeks, vowing to halt the government's advance.
"We are delivering our final warnings. We have not reached the desired results as yet," Erdogan said Wednesday. "The operation in Idlib is a matter of time. We could enter (Idlib) suddenly one night."
Akar said Turkey's military has prepared "plans A, B and C" for a possible offensive in Idlib.
So far, talks between Turkish and Russian officials have failed to reach agreements that would ease tensions there.
"While both Russia and Turkey likely seek to maintain their cooperation across Syria more broadly, growing tensions in Idlib between the two countries threatens to derail that cooperation," expert Mona Yacoubian said in an analysis for the United States Institute for Peace.
Akar said Turkey had no intention to come "head to head with Russia," insisting Turkey's aim was to ensure the Syrian government abides by the cease-fire agreement for the province.