Greece revoked Turkey’s planned participation in a May 9, Greece-hosted NATO air drill known as “Tiger Meet,” saying Turkey was “neither an ally, nor a friend,” Voice of America reports.

Greek Prime Minister Kyriakos Mitsotakis and Turkish President Recep Tayyip Erdogan meeting in March and agreeing to try to resolve their countries’ age-old differences was billed as a promising breakthrough.

But on Thursday, April 28, as armed Turkish jets streamed into Greek airspace, conducting more than 125 unauthorized flights within 24 hours, Athens retaliated.

Greece also suspended confidence-building negotiations due to begin between Greek and Turkish diplomats in May.

The snub came as the Greek Foreign Ministry summoned Ankara’s top envoy late Wednesday to protest the record number of violations over the Aegean Sea. He was called in again on Thursday as Turkish warplanes buzzed over a rash of popular holiday islands, including Rhodes and Samos, staging dangerous aerial dogfights.

Greece and Turkey, both members of NATO, have long been at odds over air and sea rights in the oil- and minerals-rich Aegean.

The disagreement has resulted in near-daily air force patrols and interception missions, mostly in disputed airspace around Greek islands that Turkey has repeatedly claimed as its own, denying any sort of violation.