France on Thursday prepared to beef up its military presence in the Mediterranean as tensions rose, prompting Turkish President Recep Tayyip Erdogan to warn of a heavy price if a Turkish ship exploring for gas in disputed waters is attacked.
Tensions between Paris and Ankara increased with the latest French announcement linked to an escalating row in the eastern Mediterranean between Turkey and Greece over gas reserves.
France criticized its NATO ally Turkey over a drone strike this week in northern Iraq, while Erdogan accused French counterpart Emmanuel Macron of seeking to bring back a colonialist structure as he visited Lebanon after last week's catastrophic Beirut explosions.
The United States meanwhile called for a rapprochement, describing France and Turkey as incredibly important NATO allies.
Existing rancor between uneasy NATO allies Turkey and Greece escalated when Ankara sent a seismic research ship named Oruc Reis to explore off the Greek island of Kastellorizo on Monday.
Turkey accompanied the Oruc Reis with several navy ships while its helicopters patrolled the surrounding skies.
Greece responded by sending its own military assets to the area to monitor Turkey's activities.
Erdogan appeared to suggest that the Oruc Reis had come under attack and that Ankara had responded accordingly.
We told them, don't you dare attack our Oruc Reis. You will pay a heavy price if you attack our Oruc Reis, we said. And they got their first answer today, Erdogan said.
France and Turkey have been at loggerheads for months over Turkey's military intervention in Libya to support the UN-recognized Tripoli government, with France saying Turkey was bringing the NATO alliance's credibility into question.
Ankara is at odds with Greece and the European Union over maritime rights in the Eastern Mediterranean over gas reserves.
The French defense ministry said two jets would arrive Thursday on the Greek island of Crete for a stay of several days, and that French military vessels took part in joint exercises with the Greek navy overnight.
The moves were designed to affirm France's commitment to free movement, to the security of maritime navigation in the Mediterranean and respect for international law, said a ministry statement.