Russian President Vladimir Putin will meet his Turkish counterpart, Recep Tayyip Erdogan, in Ankara on September 28 for talks set to touch on Syria and Iraq. Putin's one-day working visit to the Turkish capital comes three days after the two leaders spoke by telephone in a call that included a discussion of the controversial independence referendum in Iraq’s autonomous Kurdish region.

Erdogan’s office said in a September 27 statement that the two are expected to discuss bilateral relations “as well as regional and international matters, particularly Syria and Iraq.” Turkey has denounced the September 25 nonbinding referendum in Iraq's Kurdish region and accused its leader, Masud Barzani, of "treachery" for pursuing the vote.

Ankara sees the referendum, which was also fiercely opposed by the Baghdad government and much of the international community, as a threat to its national security and fears it will inflame separatism among its own Kurdish population.

Officials in Ankara said Erdogan and Putin touched on the referendum during the telephone call on September 25 and that they agreed the vote puts strains on the territorial integrity of Iraq and Syria. The Kremlin has yet to explicitly condemn the referendum, stressing instead the importance of maintaining Iraq’s territorial integrity.

Election authorities in the Kurdish region say the independence referendum passed with 92 percent support. In Syria, Moscow and Ankara support different sides in the country’s six-year war. Russia and Iran are backing Syrian President Bashar al-Assad in the conflict, while Turkey and the United States are supporting various rebel groups opposed to Assad’s rule.

But Russia, Turkey, and Iran earlier this month agreed to create a "de-escalation zone" in Idlib, an area under the control of opposition forces in northern regions. Three other "de-escalation zones" have come into effect in different parts of Syria since July.

Islamic State (IS) fighters, who captured large swathes of Syrian territory in 2014, are opposed by all sides and are being driven from most of their strongholds by the separate government and rebel campaigns.

Kremlin spokesman Dmitry Peskov said on September 27 that Putin’s visit has “absolutely pragmatic goals,” saying the two countries maintain “very close cooperation” in trade, investment, culture, military technical cooperation, and other areas. He said the two sides would “synchronize their watches on all of these issues.”

Relations between Moscow and Ankara soured after a Turkish fighter jet shot down a Russian warplane on the Syrian border in late 2015.

The two sides, however, have since established closer ties amid mounting tension in U.S.-Turkish ties on a range of issues, including Washington’s support for Syrian Kurdish fighters considered terrorists by Ankara.

Earlier this month, Turkey signed a deal with Russia to buy S-400 antiaircraft missile systems in its first major weapons purchase from Moscow. The deal, Turkey’s most significant weapons purchase from a non-NATO supplier, has raised concerns in the West over technical compatibility with NATO equipment. Both Moscow and Ankara have brushed off those concerns, with Erdogan saying on September 12 that Turkey “makes the decisions about our own independence ourselves.”