Greek officials claim that relations with Turkey ahead of elections in both countries next June are so strained that a military incident in the Aegean Sea or the eastern Mediterranean is possible, sparking a wider conflict.
Greece suspects that Turkish President Recep Tayyip Erdogan may cause a national security crisis to boost his popularity in the country ahead of elections.
In August, Erdogan suggested he might order an invasion of the Greek islands.
"We may come suddenly one night..., if you Greeks go too far, the price will be high," he said.
"By 2019, 2020 and 2021, I thought there was no chance of war. Now I can no longer say that," retired Greek admiral Alexandros Diakopoulos told Al Jazeera.
"Turkish rhetoric is going on the offensive," added Diakopoulos, a former national security adviser to Greek Prime Minister Kyriakos Mitsotakis.
The Turkish diplomat in Athens agrees that tensions exist, but adds that they are under control.
"As an embassy, we have a reasonable dialogue with our Greek colleagues. Don't believe what you read in the newspapers," Turkey's ambassador to Greece, Burak Özugergin, told Al Jazeera.
"We are all trying to prevent an incident from happening. Things are not as bad as they were in the summer of 2020, but we have to be wise because it can get worse very quickly."
The possibility of "parallel crises"
Angelos Syrigos, professor of international law at Panteion University and deputy minister of education and religious affairs, agrees.
"We are currently in Defcon 1," he told Al Jazeera, referring to the highest level of combat readiness.
"I think Turkey will try to cause many parallel crises," says Syrgios, predicting a refugee crisis followed by the presence of an oil and gas exploration vessel and a drilling vessel in an area Greece considers its maritime jurisdiction.
Relations between the two NATO allies remained strained after they came to the brink of conflict two years ago. The Greek and Turkish navies have been chasing each other in the Aegean Sea and eastern Mediterranean all summer after Turkey sent a research vessel there to look for underwater oil and gas in waters Greece claims are its own under international law.
Turkey has said it will not give up exploration activities in the area and is seeking to continue seismic surveys and exploratory drilling.
"Looking at Turkey's 2019-21 strategy, they were trying to get us to use force first. Now Turkey understands that it won't happen..., so now they are looking to do it, with the justification of portraying Greece as the conqueror of the Eastern Aegean islands", says Diakopoulos.
Turkey began objecting to uninhabited Greek islands in 1996, but last year began openly challenging Greek sovereignty over inhabited islands in the eastern Aegean Sea.
In June, Erdogan asked Greece to stop arming the Aegean islands, which have demilitarized status, and to respect international agreements. In August he hinted that he might order an invasion.
Nationalist Movement Party leader Devlet Bahçeli, Erdogan's coalition partner, posed next to a map showing Greece's eastern islands, including the Dodecanese and Crete, depicted as Turkish territory.
"We're going to throw everything out"
"The islands, where the Greeks are illegally and unjustly, are our right," Bahçeli said last month.
"The Greeks should not test our patience. If they want to drive them into the sea once more, let them know and we will throw them all out," he said.
Bahçeli was alluding to the Greco-Turkish war from 1919 to 1922, when Turkish forces defeated the Greeks, who attempted to conquer western Anatolia.
The Lausanne Treaty of 1923 gave Greece the right to the islands in the eastern Aegean Sea, but placed a limit on the military infrastructure it could have on them.
Turkey claims that Greece has exceeded these limits and therefore the islands must be surrendered.
On the other hand, the US and the European Union claim that Greek sovereignty over the islands is not in question.
Bilateral relations deteriorated further after Mitsotakis said in May last year that Turkey wanted to use the upgraded F-16 jet it had requested from the US to attack Greek airspace.
Greece recorded more than 7,000 such violations this year.
"The last thing NATO needs at a time when our focus is helping Ukraine defeat Russia is another source of instability on NATO's southeastern flank. And I ask you to take this into account when you make defense procurement decisions regarding the Eastern Mediterranean," Mitsotakis said, prompting Erdogan to say he would never meet the Greek prime minister again.
The two most important questions
Relations between Turkey and Greece have been damaged mostly by two issues, one of them being territorial waters.
According to the UN Law of the Sea (UNCLOS), "every country has the right to determine the width of its territorial waters up to a maximum of 12 nautical miles (22 kilometers)", which means that Greece can claim sovereignty over 72 percent of the Aegean Sea.
Turkey questions those 22 kilometers.
Both Greece and Turkey currently claim six nautical miles (11 kilometers) of territorial waters in the Aegean Sea, but also 12 nautical miles (22 km) of their coasts.
Another problem concerns the sovereign right to explore the seabed outside territorial waters, known as the exclusive economic zone (EEZ).
UNCLOS granted Greece an EEZ of 500,000 square kilometers in the Aegean Sea and the eastern Mediterranean.
Turkey is not a signatory to UNCLOS and opposes the provisions, and in 2019 signed a maritime agreement with Libya creating a corridor through the Greek EEZ.
The EU called the Turkish move "illegal", but earlier this month, Turkey signed another contract with Libya, for "exploration and drilling", announcing that it would send research vessels to those waters.