Greece was tracking a Turkish ship Oct. 15 that was passing the strait between the islands of Karpathos and Rhodes and as the government reiterated the six-mile territorial boundary in the seas was a red line limit.

Another Turkish ship, the energy vessel the Oruc Reis was off the island of Kastellorizo, stepping up tension after Greece withdrew its calls for sanctions against Turkish plans for drilling to give diplomacy a chance, which failed.

Minister of State Giorgos Ierapetritis said on Alpha TV that that Greece would consider any violation of the 6-nautical-mile boundary a violation of its “red lines,” but didn’t say how it would be enforced, militarily or otherwise.

“National sovereignty is a red line and when we say national sovereignty, we obviously mean national territorial waters, which, today, are defined at six nautical miles,” he said.

That came as European Union leaders were due to meet in Brussels Oct. 15-16 after earlier pulling back talks of sanctions until the end of the year after Turkey withdrew the Oruc Reis before sending it back in again, now said to be in Greek waters inside the six-mile red line limit.

Meanwhile, a Greek government airplane carrying Foreign Minister Nikos Dendias from Iraq was kept in the air for an additional 20 minutes after Turkey delayed giving it the right to cross over the country’s air space.

Kathimerini, citing reports, said the plane requested clearance from Turkish aviation authorities as it crossed the Iraqi border after setting off from Baghdad before the unusual delay, seen as a further provocation against diplomacy.

Turkey later said it was a “technical error, after the Greek Embassy in Ankara lodged a complaint over the incident.