Turkey warned Greece that a missile could hit the Greek capital unless “you stay calm,” further escalating its rhetoric against Greece.

“Now we have started to make our own missiles,” Turkish President Recep Tayyip Erdoğan said during a speech on Sunday in Samsun, in northern Turkey. “Of course, this production scares the Greeks. When you say ‘Tayfun,’ the Greek gets scared and say, ‘It will hit Athens.’ Well, of course it will.”

Tayfun, which is Turkish for “typhoon” is a short-range ballistic missile developed by Turkey. The missile, which was test-fired in October over the Black Sea and hit a target at a distance of about 560 kilometers, a range more than double that of the current missiles in Turkey’s arsenal.

“If you don’t stay calm, if you try to buy something [to arm yourself] from here and there, from America to the islands, a country like Turkey will not be a bystander. It has to do something,” Erdoğan added.

Turkey has stepped up its rhetoric against Greece in recent months amid what Ankara sees as a growing military buildup on the Greek Aegean islands, close to Turkey’s coastline. In a repeated, thinly veiled threat, Erdoğan has said: “We can come down suddenly one night when the time comes.”

Last week, Turkish Foreign Minister Mevlüt Çavuşoğlu warned Greece to stop militarizing the Aegean islands, otherwise Ankara “will take the necessary steps on the ground.”

Despite being NATO allies, the neighboring countries have been at odds for decades over a number of bilateral disputes, including maritime boundaries, overlapping claims to their continental shelves, and the long-running Cyprus dispute.

Earlier this year, Greece called upon its Western allies to put an end to Turkey’s inflammatory rhetoric or risk another Ukraine situation.