ISTANBUL (AP) — Ukrainian President Volodymyr Zelenskyy is in Istanbul on Saturday to meet with Turkey’s president.

A statement from Turkish President Recep Tayyip Erdogan’s office said the two leaders would discuss bilateral relations, characterizing them at a “strategic partnership level.”

Zelenskyy’s visit to Turkey comes amid renewed tensions in eastern Ukraine, where Ukrainian forces and Russia-backed separatists have been fighting since 2014. In a visit to troops there this week, Zelenskyy said breaches of a July truce were increasing. Separatists authorities have also accused Ukrainian forces of violating the cease-fire.

Russia has reinforced its troops along the border and warned Ukraine against trying to retake control of the separatist-controlled territory. Kyiv rejects that it is preparing for an offensive. The Russian military buildup has raised concerns in the United States and Europe.

The Turkish and Russian presidents spoke on the phone Friday. Among the issues discussed was Ukraine. The Kremlin said President Vladimir Putin expressed concern that Ukraine “recently resumed dangerous provocations on the contact line.”

Turkey is a NATO member. But Erdogan and Putin have forged a close personal relationship, sealing energy and trade deals. They have also negotiated for opposing sides in conflicts, including Syria, Libya and Nagorno-Karabakh.

Erdogan’s office also said he would discuss with Zelenskyy the living conditions of Crimean Tatars, who have ethnic links to Turks. Moscow annexed the Crimean Peninsula in 2014.