ATHENS - Greece is warning it is ready to use all its diplomatic and military might to defend its sovereignty against what it calls hostile plans by its historic foe Turkey. The direct warning follows a controversial energy deal Turkey recently signed with an element of Libya's divided government. But the tensions that have been building up recently between the two NATO allies is sparking fears of a crisis that could spill out of control and destabilize the military alliance.

FILE - Greek Prime Minister Kyriakos Mitsotakis speaks during a parliament session in Athens, Aug. 26, 2022.

Speaking to Greece's parliament, Prime Minister Kyriakos Mitsotakis advised Turkey to return, in his words, to a realm of logic. Otherwise, he warned Ankara's growing aggression and plans to claim control of areas Greece considers its territory will be stopped.

The Greek leader said geography does not change at the behest of one's decision to change or distort it. He said Greece's borders are its own and, Mitsotakis said, they are ready to be defended by its armed forces as well as by what he said are its powerful diplomatic allies.

Lawmakers answered with a roaring applause and standing ovation before Mitsotakis quickly moved to meet with the U.S. ambassador to Greece and a visiting U.S. congressional delegation of the U.S. House of Representatives.

Greece and Turkey are longtime foes but also NATO allies. Relations have cooled and warmed over the decades, often over air and sea rights.

Turkey-Greece Relations Tense Over Cyprus, Aegean Islands

Greece's threat comes after Turkey recently signed an agreement with one of Libya's two rival administrations, granting rights to an already controversial energy collaboration in waters that Greece and other countries, including Egypt and Cyprus, also claim.

The deal also comes as Greece boosts deployment of troops and U.S. military hardware on two islands closest to Turkey's borders in the Aegean Sea - actions that recently prompted a complaint from Ankara to Washington. Turkish officials called the deployment a hostile move by a NATO member and warned that Turkey would also mobilize its military in response.

Ankara sees the military buildup on the islands of Lesbos and Samos as a violation of a decades-old agreement marking the borders of the two countries.

FILE - The Greek Navy frigate HS 'Spetsai' patrols in the Aegean Sea, off the Turkish coast, April 21, 2016.

Turkey's president, Recep Tayyip Erdogan, has gone further in the last few days, denouncing Greek ownership of several islands in the Aegean - remarks that have prompted Athens to escalate talk of its willingness to defend itself in the face of what it calls Turkish aggression.

The European Union has chided Turkey for its stance and Washington is already at odds with Turkey for purchasing a missile defense system from Russia, a move NATO countries say puts the alliance at risk.

Analyst George Tzogopoulos explains the broader repercussions that this growing crisis could bring to the NATO alliance and how Russia, its greatest opponent, may exploit it.

Turkey-Greece Tensions Could Disrupt NATO Unity, Experts Warn

"It's crystal clear in Washington that Turkey is not considered a reliable partner and within that context, Greece is. So, this situation is creating a new dynamic within the Eastern Mediterranean and NATO itself but most importantly, in the aftermath of Russia's invasion of Ukraine, the US is working closer with reliable partners, and this is fueling the aggressive rhetoric from the other side [Turkey]," he said.

There are hopes within Europe, he says, that the situation may be contained. But Tzogopoulos warns the alternative could prove dangerous.

"If Turkey continues, the cohesion of NATO's southeast flank will be jeopardized, news that will be welcomed in Moscow," he said.

Diplomatic sources in Athens tell VOA that senior Greek officials will visit the Middle East in the coming days to try and overturn Turkey's latest energy pact before Ankara sends out drilling vessels to contested waters, as part of a bid to avert a larger conflict.