The link provides the full text of the letter.

Response from Athens to Turkish expansionism
Letter sent to UN Secretary-General Antonio Guterres refutes Ankara’s claims regarding the Aegean islands and its calls for their demilitarization

The letter also raises Ankara’s declaration of threat of war (casus belli) in 1995 in case Greece “extends its territorial sea beyond the current limit of 6 nautical miles, exercising its lawful right in accordance with international law for extension up to the limit of 12 nautical miles.”

It concludes with the reminder that Turkey “has invaded and illegally occupies, apart from a part of Cyprus, also parts of Iraq and Syria,” and maintains forces and mercenaries in Libya. Therefore, Greece “is fully justified to take all elementary precautionary measures to ensure that it will be able to exercise its inalienable right to self-defense.”