'Sanctions and threats' won't deter Turkey: Erdogan
The search for oil and gas in contested energy-rich waters not far from Cyprus has pitted Turkey against its uneasy NATO ally Greece and the entire EU bloc.
Turkey's decision to send a scientific vessel accompanied by a small navy fleet into the volatile region on Monday prompted Greece to dispatch in its own military assets to observe what was going on.
France on Thursday also announced it was "temporarily reinforcing" its presence in the eastern Mediterranean in support of Greece.
But on Saturday Erdogan was adamant.
"On this question, our country is entirely in the right and we will continue to defend our rights, using all the means at our disposal,," the Turkish head of state promised in televised comments.
"We will not back down in the face of sanctions and threats," he insisted.
Turkey argues that Greece is using its control of a few tiny islands off the coast of Turkey to claim an outsized share of the Mediterranean Sea.
It also cites examples of past international agreements that gave the coastal power the right to waters despite another nation's islands near its shores.
The diplomatic jostling saw Greek Foreign Minister Nikos Dendias seek Washington's backing at a meeting in Vienna with US Secretary Mike Pompeo this week.
Yet both Washington and Brussels are keen to avoid head-on confrontations with Erdogan.
A European official told AFP that German Chancellor Angela Merkel warned Erdogan in July that Turkey would face EU sanctions if it drills in Cypriot waters or off the Greek island of Kastellorizo.
On Thursday, EU chief Charles Michel underlined EU solidarity with member states Greece and Cyprus and urged Erdogan to "de-escalate tensions and avoid provocations".
Erdogan said his country is ready for dialogue, but again attacked Greece on Saturday, accusing Athens of mistreating the Muslim and Turkish-speaking minorities on its territory.
The Greek authorities "must, without delay, end to the measures which resemble state terrorism. There are attacks on our mosques and our schools", the Turkish president declared, without giving any details.