A Kurdish-controlled western Syria could prompt Turkey to invade Syria, Prime Minister Recep Tayyip Erdoğan said in an interview with Turkish media on Wednesday.

“If a formation that’s going to be a problem, if there is a terror operation, [if] an irritant emerges, then intervening there would be our most natural right,” Erdoğan said.

Turkey has repeatedly struck PKK operatives and bases in Iraqi Kurdistan since that region began exerting autonomy after the 1991 Gulf War.

The presence of Kurdish groups affiliated with the PKK could provide Turkey with a casus belli in Syria, analysts believe. The PKK, a Kurdish rights group recognized by the US, the EU, and Turkey as terrorist organization, has waged a decades-long conflict against Ankara.

Erdoğan’s rhetoric regarding Syria has grown increasingly belligerent since the uprising there broke out 16 months ago. Last month, Syria shot down a Turkish Air Force jet, which nearly prompted an military retaliation by Turkey.

Ankara warned Syria earlier this week that any cross-border violence would be repaid in turn.