Ankara, Turkey – An attack by Syrian government forces killed five Turkish soldiers in northwest Syria on Monday, threatening further escalation in the region after another deadly artillery strike last week.

Turkish defence officials said five other troops were wounded in “intense” shelling in Taftanaz in the northwestern province of Idlib, the last rebel-held stronghold in Syria.

Turkey immediately responded and “neutralised” more than 100 enemy targets, the defence ministry said in a statement.

“A heinous attack occurred today in Idlib, where our military serves, pursuant to our rights under international law, to end the violence and mitigate the humanitarian crisis,” Fahrettin Altun, Turkish President Recep Tayyip Erdogan‘s communications director, wrote on Twitter.

“Turkey retaliated against the attack to destroy all enemy targets and avenging our fallen troops. The war criminal, who ordered today’s heinous attack, targeted the entire international community, not just Turkey.”

Turkish Foreign Minister Mevlut Cavusoglu commented that Ankara had “responded to the cowards”, adding: “Our glorious army will continue to do what is necessary.”

Last week, eight Turkish military personnel were killed in a similar attack on Saraqeb, south of Taftanaz. The Turkish response at the time left at least 13 Syrian soldiers dead.

Following that attack, Ankara warned Syrian government forces to retreat to lines agreed in a 2018 ceasefire by the end of February. However, Syria‘s military promised to continue its campaign, which is focused on seizing two highways linking Aleppo to other government-controlled areas.

The most recent attack came as a Russian delegation arrived in Ankara for further talks on fighting in Syria. Russia and Iran support Syrian President Bashar al-Assad while Turkey backs some of the opposition groups that have made Idlib their final stronghold.

Omer Celik, a spokesperson for Turkey’s ruling Justice and Development Party, said Erdogan could meet with his counterpart Russian President Vladimir Putin if the talks reached a stalemate.

“Negotiations are ongoing with the visiting delegation and, so far, no concrete conclusion has been reached,” he said. “The Turkish side has made its own concrete position very clear. Negotiations will continue.”

Celik added: “The Turkish Armed Forces will continue their efforts in Idlib until the regime withdraws.”

Soner Cagaptay, director of the Turkish research programme at the Washington Institute for Near East Policy, said Turkey would call on Moscow to put pressure on the Syrian government.

“Assad regime forces killed 13 Turkish troops in one week alone,” he said. “Ankara has to punish Assad and Russia has to agree to this, but that doesn’t mean Putin will allow Erdogan steamroll Assad completely out of Idlib.”