Turkish Foreign Minister Mevlut Cavusoglu has kept up insistence that Greece must demilitarize Greek islands near Turkey’s coast, citing the 1923 Treaty of Lausanne that Turkey doesn’t recognize.

That comes amid more Turkish claims over the waters in the Aegean and the East Mediterranean, where it’s drilling for oil and gas off Cyprus and plans to do the same around Greek islands.

“We sent two letters to the UN. We sent them because Greece is violating the demilitarization regime of the islands. These islands were ceded to Greece by the Treaties of Lausanne of 1923 and Paris of 1947 on the condition of their demilitarization. But Greece has been violating this regime since the 1960s,” he told the Turkish TRT television network.

“In the letter we wrote we mentioned that Greece violates the terms of the treaties, these islands were given under conditions, and if Greece does not change its position, then the sovereignty of these islands is debatable,” he added.

Turkish President Recep Tayyip Erdogan has said he covets return of islands close to Turkey’s coast, some of them so close he said Turks can even hear roosters crowing on them.