Turkish President Recep Tayyip Erdogan ramped up the rhetoric on Greece last Saturday when he threatened to “come down suddenly one night.”

Kathimerini, Greece’s biggest daily reported that Erdogan has reused that phrase when talking about military operations into Syria and Iraq against Kurdish militants that Turkey deems existential threats. And he made good on that threat several times with military incursions in Syria against Kurdish fighters.

Speaking at an aerial technology festival in Samsun, where Turkey showcased the prototype of an unmanned fighter jet, Erdogan lashed out at Greece.

Turkey accused Greece of using Russian-made S-300 missile systems in Crete to lock onto Turkish jets in August. Ankara claimed Greek F-16s harassed Turkish jets by putting them under a radar lock during a NATO mission over the eastern Mediterranean. Turkey is submitting complaints with NATO. Athens has also accused Turkey of violating its airspace.

Both Greece and Turkey are NATO members, however they have had decades-old disputes over territorial claims in the Aegean Sea, the Turkish invasion of Cyprus and the occupation of the island’s north since 1974, and disagreements over airspace.

The friction has brought them to the brink of war three times in the last half-century.

Turkey claims Greece is violating international agreements by militarizing islands in the Aegean Sea.

“You occupying the islands doesn’t bind us,” Erdogan said Saturday. “When the time comes, we’ll do what’s necessary. As we say, we may come down suddenly one night.”

He added: “Look at history, if you go further, the price will be heavy.”

“We have one sentence to Greece: Don’t forget Izmir (Smyrna),” Erdogan said, in a reference to a crushing defeat of Greek forces in the western Turkish mainly Greek city of Smyrna by the Turkish military in 1922. The Turkish forces, including paramilitaries burned the city, and the forced expulsion of Greeks indigenous to Tukey began in the wake of the defeat of Greek forces.

Erdogan and Greek Prime Minister Kyriakos Mitsotakis did hold rare talks over lunch in Istanbul in March, but the bonhomie was short-lived. In May, Erdogan said he would no longer speak with Mitsotakis after the Greek prime minister visited Washington where he pushed to acquire F-35 stealth fighter jets while lobbying against Turkey’s attempts to upgrade its F-16 fleet.

Erdogan said in July that Turkey didn’t have interest in war with Greece but said the country should stop violating Turkish airspace.