(Bloomberg) -- Turkey warned Greece its soldiers on a tiny island violate a 1947 peace treaty, stoking tension between the two NATO members over energy resources in the Mediterranean.

With Turkish media featuring images of Greek soldiers arriving on the island, the Foreign Ministry in Ankara said Sunday “we will not allow such a provocation just across our shores.” In contrast, a person familiar with the Greek government’s stance said soldiers are already stationed on the island and the event was a routine troop rotation.

While Greece played down the military move’s significance, the friction is the latest sign of regional conflict between two countries that went to war over Cyprus in 1974 and are at odds over exclusive economic zones while occupying key positions on the North Atlantic Treaty Organization’s eastern flank.

Kastellorizo, a 12-square-kilometer (4.6-square-mile) island off the Turkish coast and the most distant Greek outpost in the eastern Mediterranean, is once again at the center of the dispute. Turkey argues it should be demilitarized — the flashpoint for the latest confrontation. The Greek government had no immediate comment on Sunday.

Greece says islands must be taken into account in delineating a country’s continental shelf, in line with the United Nations law of the sea, a convention Turkey hasn’t signed. Turkey argues that a country’s continental shelf should be measured from its mainland, and that the area south of Kastellorizo therefore falls within its exclusive zone.

Turkey is facing the threat of European Union sanctions over its energy exploration in the eastern Mediterranean, which could escalate to assets, ships and restrictions on Turkish access to European ports and supplies. Turkey has rebuffed the EU, saying it will keep up exploration activities south of Kastellorizo at least through Sept. 11.

Turkey and France

President Emmanuel Macron, who has boosted France’s naval presence in the region, said Friday that Turkey hasn’t behaved like a NATO ally in recent years. Turkish President Recep Tayyip Erdogan struck a defiant tone on Sunday, saying his country is ready to pay the price for defending its interests in the eastern Mediterranean.

He questioned whether Greeks and the French are willing to make similar sacrifices for their “ambitious and incompetent rulers.”

The maritime boundary in the Aegean is one of the most contentious issues in Greek-Turkish relations, with each country trying to mark out where it can exploit seabed oil and mineral deposits.

Turkey Wrangles With France Over East Mediterranean Energy Rift

Turkish Foreign Minister Mevlut Cavusoglu on Saturday warned Greece against extending its territorial waters from six to 12 nautical miles. He said a 1995 Turkish parliament decision that described such an move as a cause for war remains valid.

Tiny but Strategic

Kastellorizo became part of Greece in 1947 after Italian and British occupation during World War II. Turkish attack helicopters scrambled this month when a Greek navy ship made a port visit to the island.

Turkey argues the treaty calls for Kastellorizo to be demilitarized and “if Greece continues to take steps that escalate tensions in the region, it will end up being the loser,” Foreign Ministry spokesman Hami Aksoy said in an emailed statement Sunday.

Offshore gas reserves around Cyprus are especially contentious since the Republic of Cyprus is an EU member and officially has sovereignty over the entire island.

Cyprus has been effectively divided since Turkey’s military captured the northern third in 1974, following a coup attempt in which a military junta in Athens sought to unite Cyprus with Greece. The Turkish minority’s self-proclaimed state in the north, recognized only by Ankara, lays claim to any energy resources discovered off its coast.

Turkish F-16s Confronted Greek Jets Near Disputed Area

Turkey and Greece came to the brink of war three times between 1974 and 1996 over Cyprus and territorial rights in the Aegean. In 2006, a Greek war pilot died after colliding with a Turkish jet in one of endless mock dogfights over the Aegean.

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