Greece has announced an extension of its territorial waters to the west in a major shift of policy amid is standoff with Turkey in the eastern Mediterranean.
Greek Prime Minister Kyriakos Mitsotakis said on Wednesday his country was planning to exercise its legal right to extend its territorial waters along its western coastline from six to 12 nautical miles.
The decision will not directly impact the dispute with Turkey but Mr Mitsotakis said the change marked a major move away from decades of “passive” foreign policy.
Tensions between Athens and Ankara have escalated close to breaking point in recent weeks over access to Economic Exclusive Zones (EEZ) around Greek islands in the Eastern Mediterranean.
Greece and the EU have said Turkey's exploration operations in the area are illegal. Turkey has said it should have access to waters on the islands because they lie on its continental shelf.
The move from Athens comes during a flurry of diplomatic activity in attempts to de-escalate tensions between the two nations.
Speaking ahead of an EU defence ministers’ meeting, Nato Secretary-General Jens Stoltenberg called for dialogue between the two allies.
“We are concerned about the situation in the eastern Mediterranean. What we need is de-escalation, is dialogue,” he said.
“Turkey and Greece have both been important Nato allies for many years. And we need to find a way to resolve the situation in the eastern Mediterranean based on the spirit of Allied solidarity and international law ,” the Nato chief added.
EU foreign ministers are to meet to discuss their response to the crisis on Thursday.
France on Wednesday said military exercises in the eastern Mediterranean along with Greece, Italy and Cyprus had begun and were aimed at promoting respect of international law.
Defence Minister Florence Parly said on Twitter that three Rafale jets, a frigate and a helicopter would take part for France in the exercises.
Turkish president Recep Erdogan continued to rail against Greece. "Turkey will take what is its right in the Mediterranean, in the Aegean and in the Black Sea," Erdogan said.
"Just as we have no eyes over anyone's territory, sovereignty and interests, we will never compromise on what belongs to us. We are determined to do whatever is necessary in political, economic and military terms."
"We invite our interlocutors to get their act together and to avoid mistakes that will lead to their ruin," he added.
On Wednesday Germany’s foreign minister has called on Greece and Turkey to step back from the brink in the eastern Mediterranean
Heiko Maas travelled between Turkey and Greece, to bolster Germany's efforts at mediation between the two countries.
"What we really need is a willingness for dialogue," Mr Maas said during a joint news conference with his Turkish counterpart, Mevlut Cavusoglu, on Tuesday. "A further escalation is not in the interest of Greece, not in the interest of the EU and also not in the interest of Turkey.
"The situation is very risky," Mr Maas said. "Whoever moves closer and closer to the abyss can at some point fall down. That's a development which we want to avoid.
"Nobody wants to solve this conflict militarily, which would be absolute insanity,” he said. “But the willingness for dialogue is there.”
Greece, France and Cyprus have called for sanctions against Ankara over its actions in the eastern Mediterranean.
The arrival of the Turkish research vessel the Oruc Reis prompted a build-up of dozens of naval vessels and aircraft in the area, drawing in other nations such as France.
After their meetings with Mr Maas, both Mr Cavusoglu and Greek Foreign Minister Nikos Denidias said they were open to discussions.
Turkey, however, continued to hit out, blaming Greece for the break-up of previous efforts for a dialogue earlier this month.
"Turkey is ready to hold talks with everyone for the fair sharing [of resources]," Mr Cavusoglu said. "Turkey has always supported dialogue with Greece and has been in favour of resolving problems through diplomacy, not conflict,” he said.
"We are not the ones that increase tensions. Greece must forego its spoiled acts. It should not allow itself to be egged on by other countries and put itself into risk. If you take wrongful steps... we would do the necessary without any hesitation."