NICOSIA — Greece’s prime minister said Monday that his government wants to take full advantage of a developing positive political climate with neighboring Turkey in order to improve bilateral relations despite a string of decades-old disputes.

But Greek Prime Minister Kyriakos Mitsotakis said that doesn’t mean Turkey has “substantially changed” its stance on key differences between the two countries and needs to “decisively abandon its aggressive and unlawful conduct” against Greece’s sovereignty and territorial integrity.

Turkey and Greece remain at odds over maritime boundaries in the eastern Mediterranean, a dispute that affects irregular migration into the European Union, mineral rights and the projection of military power.

Mitsotakis said that he agreed with Turkish President Recep Tayyip Erdogan during a NATO summit in Vilnius, Lithuania, on July 11-12 to initiate new “lines of communication” and to maintain “a period of calm.”

High-level talks between the the two countries are expected to take place in the Greek city of Thessaloniki later this year.

However, the Greek prime minister said that Erdogan’s outreach to the EU can’t come at the expense of efforts to heal Cyprus’ nearly half-century ethnic division.

Speaking after talks with Cypriot President Nikos Christodoulides, Mitsotakis said that he told Erdogan that improved European-Turkish ties can’t exclude a Cyprus peace accord and that the issue can’t be “left by the wayside.”

Turkey and the breakaway Turkish Cypriots have insisted on a two-state solution since July 2017 when the most recent round of U.N.-facilitated peace talks collapsed.

That position overturned a long-standing agreement sanctioned by the U.N. Security Council in numerous resolutions that any peace deal would aim for a reunified Cyprus as a federation made up of Greek and Turkish speaking zones.

Cyprus was split in 1974 when Turkey invaded following a coup by supporters of union with Greece. Only Turkey recognizes a Turkish Cypriot declaration of independence in the island’s northern third, where more than 35,000 Turkish troops are stationed.

On Friday, Turkish Cypriot leader Ersin Tatar repeated that peace talks could resume only if Greek Cypriots recognize the Turkish Cypriots’ “sovereign equality.”

Christodoulides said Monday that any improvement in European-Turkish relations should be based on reciprocal action by Turkey, adding that the EU prioritizes a Cyprus peace deal in line with U.N. resolutions.