Prime Minister Recep Tayyip Erdoğan warned on Sunday that Turkish forces may cross the border into Syria in pursuit of Kurdish separatists. He accused Syrian president Bashar al-Assad of supporting the Kurdish insurgency.

Erdoğan spoke with Turkish television on the day that fourteen Kurdish militants were killed in simultaneous raids on four Turkish border posts. Six border guards died in the clashes.

Kurdish militant activity in the border area between Iraq, Syria and Turkey has increased in recent months. In the absence of Syrian security forces, separatists aligned with the Turkish Kurdistan Workers’ Party (PKK), which is considered a terrorist organization by Turkey and its NATO allies, have been able to stage attacks on Turkish border posts and take over entire Syrian towns.

Last week, Turkish tanks carried out military exercises near the Syrian border, mere kilometers from towns that are now under Kurdish control. Turkey has increased its army presence on the border since one of its fighter planes was taken down by Syrian air defenses in June.

Erdoğan did not “rule out” the possibility of Turkish forces crossing the border to suppress the Kurdish uprising. “We have three brigades along the border currently conducting maneuvers there. And we cannot remain patient in the face of a mistake that can be made there.”

Earlier, Erdoğan insisted that, “It is out of question for us to tolerate a structure of the terrorist organization in north of Syria and permit the presence of a threat to Turkey there.”

Turkish forces in recent years have crossed into northern Iraq numerous times in pursuit of Kurdish insurgents. At the same time, it has fostered close commercial and diplomatic relations with the Kurdistan Regional Government there, to the extent that it antagonized the central government in Baghdad when it began importing Kurdish oil last month.

That relationship could be strained if Iraqi Kurds throw in their lot with their Syrian counterparts. The president of Iraq’s Kurdish province Masoud Barzani admitted earlier this month that Syrian Kurds who had defected from Assad’s army were being trained in his territory. “This was aimed at filling the vacuum that will be created” if the Ba’athist regime collapses, he explained.

Less than two million Kurds live in Syria. Turkey’s Kurds, more than eighteen million, comprise some 20 percent of the country’s population. Ankara has battled the PKK’s quest for independence since the early 1980s. Many of its fighters are drawn from Syria’s Kurdish minority.

Turkey cannot allow northeastern Syria to become a safe haven for insurgents but if it intervenes, it not only risks losing the trust of the Syrian opposition which, under the leadership of a Kurd, has been allowed to organize on Turkish soil; it could instigate a war with Syria proper because President Assad will likely regard an incursion as the first step toward toppling his government.

Correction: An earlier version of this story erroneously claimed that there are more than seventy million Kurds in Turkey. This is, in fact, Turkey’s total population.