Tensions are escalating again in the Eastern Mediterranean following a series of Turkish incursions in Greek waters.

Greek Prime Minister Kyriakos Mitsotakis convened the government’s national security council and held emergency talks with European leaders in Brussels and NATO Secretary General Jens Stoltenberg over the latest Turkish actions.

Stoltenberg Tweeted after his call with Mitsotakis that “the situation must be resolved in a spirit of Allied solidarity and in accordance with international law.”

Turkey announced on Monday morning (local time) that a research vessel would be conducting exploratory drilling in an area between Cyprus and Greece.

Ankara kicked off its latest unilateral, illegal moves when it issued a formal “Navtex,” or international maritime safety message, announcing its research vessel Oruc Reis and two auxiliary vessels would be conducting exploratory drilling from August 10-23.

The action caused a flurry of activity in Athens and throughout Europe, with a stern response coming from Washington later in the day.

“The United States is aware that Turkey has issued a notification to other ships of survey activity in the Eastern Mediterranean. We urge Turkish authorities to halt any such plans for operations and to and to avoid steps that raise tensions in the region,” a State Department spokesperson said.

“The United States is deeply concerned by Turkey’s stated plans to survey for natural resources in areas over which Greece and Cyprus assert jurisdiction in the Eastern Mediterranean. Such actions are provocative and raise tensions in the region,” the spokesperson said.