Greece’s prime minister, Kyriakos Mitsotakis, has welcomed a decision by France to dispatch war frigates to the eastern Mediterranean as a standoff with Turkey over regional energy reserves intensifies.

With tensions between Athens and Ankara causing growing international alarm, Mitsotakis described the vessels as “guarantors of peace”.

“The only way to end differences in the eastern Mediterranean is through international justice,” he told reporters after holding talks in Paris with the French president, Emmanuel Macron. “Greece and France are pursuing a new framework of strategic defence.”

Mitsotakis was in the French capital on a visit aimed at rallying EU support at a time when hostile relations with Turkey have eclipsed all other issues on the agenda of his near seven-month-old government [1].

Macron pledged France would step up its strategic bond with Greece, accusing Turkey of not only exacerbating regional tensions but failing to stick to its promised course of action in war-torn Libya.

“I want to express my concerns with regard to the behaviour of Turkey at the moment … we have seen during these last days Turkish warships accompanied by Syrian mercenaries arrive on Libyan soil [2]. This is an explicit and serious infringement of what was agreed [at last week’s peace conference] in Berlin. It’s a broken promise.”

The Gallic-Greek alliance cements what officials in Athens are calling a renewed diplomatic push to counter Turkish belligerence in the Mediterranean.

Greece’s defence minister, Nikos Panagiotopoulos, recently went as far as to warn that armed forces were “examining all scenarios, even that of military engagement” in the face of heightened aggression from Ankara. Rejecting Turkish demands that Greece demilitarise 16 Aegean islands, he accused Turkey of displaying unusually provocative behaviour.

The demand, made by his Turkish counterpart, Hulusi Akar, follows a dramatic surge in recent months in the number of violations of Greek airspace by Turkish fighter jets. “Greece does not provoke, does not violate the sovereign rights of others, but it doesn’t like to see its own rights violated,” said Panagiotopoulos.

Tensions between the Nato allies prompted Donald Trump to take the unprecedented step of voicing concerns over the situation in a telephone call with the Turkish president, Recep Tayyip Erdoğan, on Monday.

The White House spokesman Judd Deere tweeted that in a conversation focusing on Libya and Syria, the US president had also “highlighted the importance of Turkey and Greece resolving their differences in the east Mediterranean” [3].

Friction between the two neighbours has not been so acute since the invasion of Cyprus in 1974 [4] – an operation that resulted in the island’s permanent division that is still viewed by Ankara as one of its greatest modern military successes. Privately, Greek officials liken the mood music between the rival countries to 1996, when a military clash over an Aegean islet inhabited solely by goats was narrowly averted after Washington stepped in. “The intervention has been welcomed,” said one well-placed MP. “But whether it will help avoid armed confrontation is far from sure.”

Regional tensions have escalated as Turkish anger has risen over conflicting claims to potentially massive energy reserves in the eastern Mediterranean.

Erdoğan’s ire has so far been aimed at Cyprus, where a feud over exploration rights has deepened following the discovery of natural gas deposits in waters around the island [5]. Ignoring Turkish anger at not being included, the internationally recognised Greek Cypriot government has forged ahead with the search, commissioning international energy companies, including the French multinational Total, to explore allocated blocs off the island for underwater resources.

This month the Turkish president threatened to send more drill ships to the region in retaliation. But an accord reached between Ankara and the UN-backed government in Tripoli in December, delineating new maritime boundaries between the two nations [6], has taken the bilateral animosity to a higher level.

Waters south of Crete are directly challenged under the agreement with officials in Athens viewing it as a deliberate and unprecedented attempt to undermine the country’s sovereignty. Standing alongside Mitsotakis after their talks, Macron said France “deplores the Turkish-Libyan deal in the clearest terms”.

“What we are seeing is a far more revisionist and aggressive Turkey aiming at change of borders be it on land or sea,” said the international relations professor Aristotle Tziampiris at the University of Piraeus. “That, and Erdoğan’s increasing authoritarianism, is the cause of such tensions and consternation with Greece,” he said. “To counter the aggression, Athens is resolved to strengthen partnerships and strategic alliances, be it with France, other EU allies or the US.”

Tziampiris does not believe the tensions will lead inexorably to confrontation, but the possibility of the two neighbours slipping involuntarily into conflict is real.

“The chances of war are slim, not least because it would be too much of a lose-lose situation,” he said. “But the chances of a [hot] incident, by design or accident, are very real and that is what is worrying us all.”

Helena Smith in Athens