Turkey issued a Navtex during a Greek naval exercise in the Aegean, reiterating its long-standing claim that certain Greek islands should be “demilitarized.”

In its notice, Turkey listed several islands, asserting that “military activity should not be conducted in the territorial waters of those islands.”

It further warned that any military activities in these areas “may endanger the safety of navigation in violation of international treaties.”

The Greek exercise, already underway in the Aegean, followed an earlier Turkish Navtex issued late Sunday, which announced that starting Monday and lasting 10 days, the research vessel Piri Reis would conduct scientific surveys in parts of the Aegean Sea.

The drill, which began at 5 a.m., involves the activation of Delta Force, a joint formation of the Hellenic Armed Forces.

Athens said the exercise was aimed at demonstrating readiness and determination to defend national sovereignty.