Athens, Greece – Turkish President Recep Tayyip Erdogan on Wednesday accused Greece and Southern Cyprus of failing to fulfill “promises” made during negotiations within the European Union and NATO and said his country would continue to give them “the response they deserve.”

President Erdogan’s comments came days after Turkey redeployed its search vessel, Oruc Reis, for a new energy exploration mission in Blue Homeland / Mavi Vatan waters in the Eastern Mediterranean, reigniting tensions with Greece and Southern Cyprus over sea boundaries and exploration rights. Two navy frigates are shadowing the search vessel.

Those tensions had flared up over the summer, prompting a military buildup, bellicose rhetoric and fears of a confrontation between the two NATO members and historic regional rivals.

“Our Oruc Reis has returned to its duty in the Mediterranean,” Erdogan told legislators of his ruling party in a speech in parliament. “We will continue to give the response they deserve on the field, to Greece and the Greek Cypriot administration who have not kept their promises during talks within the EU and NATO platforms.”

He didn’t spell out what the promises were but Turkish officials have been accusing Greek officials of engaging in a series of “provocations” despite efforts to revive the so-called exploratory talks between the neighbors that were aimed at resolving disputes and were last held in 2016.

Heiko Maas, the foreign minister of Germany, which has been mediating between Greece and Turkey in a bid to ease the tensions, criticized Turkey on Tuesday for taking “unilateral steps” in the Eastern Mediterranean which he said were undercutting efforts to de-escalate tensions. The US State Department issued a statement deploring Turkey’s move.

Turkey says the Oruc Reis was redeployed following provocative acts by Greece, including a decision to hold military drills in the Aegean Sea on Turkey’s main national holiday.

During his speech, Erdogan also rebuffed international criticism over Turkey’s move to open the beachfront of Northern Cyprus’ fenced-off suburb of Varosha in divided Cyprus’ Turkish Cypriot north.

“The fenced-off Varosha region belongs to the Turks of northern Cyprus. This should be known as such,” he said.

Varosha remained off-limits and in Turkish military control after its Greek Cypriot residents fled before advancing troops in 1974 when Turkey landed and sliced the island along ethnic lines after a coup by supporters of union (ENOSIS) with Greece.

Separately, Erdogan declared that he would on Saturday announce details on the discovery of a new natural gas reserve off the Black Sea coast. In August, Turkey announced the discovery of 320 billion cubic meters of gas, which the country said would help ease the country’s dependence on imports.