Erdogan said Turkey is determined to push Syrian government forces beyond Turkish observation posts in the northwestern Idlib region by the end of February, and he warned allied Syrian rebels not to give government forces an excuse to attack.

Violence has flared in Idlib, just south of Turkey’s border, in recent weeks as government forces have made gains in their campaign to eliminate the last insurgent bastion after the country’s nine year war.

“If there is the smallest injury to our soldiers on the observation posts or other places, I am declaring from here that we will hit the regime forces everywhere from today, regardless of Idlib’s borders or the lines of the Sochi agreement,” Erdogan said, referring to a 2018 ceasefire accord.

“We will do this by any means necessary, by air or ground, without hesitating, without allowing for any stalling,” he told members of his AK Party in Ankara. Russia, which has an air base in Syria, has controlled Idlib’s air space for several years.

The Turkish military casualties have strained ties between Ankara and Moscow. The TASS news agency quoted the Kremlin as saying Russian President Vladimir Putin and Erdogan agreed in a phone call that the sides would continue contacts on Syria.

Erdogan said Turkey-backed rebels have mobilized to push Syrian government forces out of Idlib, but added they must remain disciplined.

“We have given the message that we will act without compromise to those from the opposition groups who act in an undisciplined way and give the regime an excuse to attack,” he said.

Erdogan said on Tuesday the Syrian government would pay a “very heavy price” for attacking Turkish troops, including five killed on Monday and eight Turkish personnel killed a week earlier.

“We gave the necessary responses to the Syrian side at the highest level. Especially in Idlib, they got what they deserved. But this is not enough, it will continue,” he said in Ankara, adding he would announce on Wednesday a detailed plan for Idlib.

Talks in Ankara between Turkey and a Russian delegation ended on Monday without agreement on halting the fighting, a Turkish diplomatic source said.

Reporter’s code: 50101