ATHENS — U.S. Secretary of State Mike Pompeo visited a U.S. naval base at Souda Bay on the southern Greek island of Crete Tuesday, ahead of a meeting with Greece's prime minister on the second day of his trip to the country. 

Pompeo began his five-day regional tour in the northern Greek city of Thessaloniki, where he met with Greek Foreign Minister Nikos Dendias and discussed issues including a recent severe escalation in tension between Greece and Turkey in the eastern Mediterranean.

Pompeo said Washington will use its diplomatic and military influence in the region to try to ease the volatile dispute over maritime boundaries and energy exploration rights between the two neighbors and NATO allies.

The United States and Greece "reiterated their dedication to enhancing their close cooperation as NATO allies, using all appropriate means at their disposal, in order to safeguard stability and security in the wider region," the two countries said in a joint statement after the meeting in Thessaloniki.

Greek-Turkish relations deteriorated sharply this year, leading to fears the dispute could lead to open conflict. 

Turkey sent a research vessel, accompanied by warships, to prospect for energy resources in an area Greece claims is on its own continental shelf and where it claims exclusive economic rights. Athens sent warships of its own to the area. 

European Union members are to discuss potentially imposing sanctions on Turkey for its actions later this week.

However, tension has eased somewhat in recent days, and Pompeo welcomed a decision by both sides to restart exploratory talks, saying maritime disputes should be solved through dialogue, not demonstrations of power.

"We've watched the Greeks move in that direction trying to achieve that," he told Greece's ANA state news agency Monday. "We hope the Turkish government will see it the same way, and we hope the exploratory talks not only get kicked off right, but it's important that they're resolved in a way that delivers outcomes that each of the two nations find more than acceptable."

Amid the tension with Turkey, Greece has announced major arms purchases, including fighter jets from France, as well as warships, helicopters and weapons systems. 

Last October, Pompeo visited Athens and signed a revised defense cooperation agreement with Greece that provided for increasing joint U.S.-Greece and NATO activity at three locations in Greece as well as infrastructure and other improvements at Souda Bay.

Pompeo flew to Crete Monday evening, and spent the night at the home of Prime Minister Kyriakos Mitsotakis. The two were scheduled to meet for talks Tuesday morning after the visit to Souda Bay and a Greek frigate.

About 1,500 people in Thessaloniki protested Pompeo's visit Monday evening, carrying signs reading "The hawk of war is not welcome in our country," and "The murderers of the peoples are not welcome." A smaller protest was also held in the Greek capital, Athens. The protests were organized by left-wing groups and the Communist Party.