Greek-Turkish relations appear to be entering a more difficult phase, as Turkey reacts sharply to Greece’s accelerating military modernization and the deepening of its defense ties with Israel. The agreement surrounding the so-called “Achilles Shield,” Greece’s new air-defense architecture, has added another layer to tensions that had already been building in the Aegean and Eastern Mediterranean.

Turkish President Recep Tayyip Erdoğan has responded forcefully to Greece’s defense spending, while Ankara has once again raised longstanding claims over the demilitarization of Greek islands and the existence of so-called “gray zones” in the Aegean. The rhetoric marks a notable departure from the more conciliatory atmosphere that followed the signing of the Athens Declaration in December 2023.

From Ankara’s perspective, the “Achilles Shield” is not simply another Greek procurement program. Turkey sees the development as a potential shift in the military balance in the Aegean, particularly because it is linked to Greece’s expanding strategic and defense relationship with Israel. That relationship has generated growing concern in Ankara and among parts of the Turkish public, adding to domestic pressure on the government to take a tougher stance toward Athens.

Erdoğan’s warning from across the Kastellorizo channel

The most striking element of Erdoğan’s latest intervention was his reference to Kaş, the Turkish coastal town directly opposite the Greek island of Kastellorizo.

“If we were to send a message from Kaş to Greece, they would hear it, wouldn’t they?” Erdoğan said, linking his criticism directly to Greece’s military buildup. He accused Athens of pursuing the “wrong path” by strengthening its military presence on the eastern Aegean islands, despite what he described as Ankara’s efforts to maintain good relations.

The comments represent a clear shift in presidential rhetoric compared with the period following the Athens Declaration. More importantly, they do not appear to be an isolated incident. They form part of a broader series of Turkish moves that have gradually brought almost all of the traditional disputes between the two countries back into focus.

The Turkish president, who for months now, both he and his top ministers, have been attacking Greece over the Armed Forces' armaments program, was annoyed yesterday because Greece is expressing objections to the sale of F-35s to Turkey. And in fact, in response to questions - in mild tones, however - he mischaracterized Kyriakos Mitsotakis' stance, while attempting to downplay the casus belli and appear ready to resolve the Aegean "issues".

Turkey is seeking to open a new chapter in its relations with both the United States and the European Union.