What's at stake when Turkey's Erdogan meets Russia's Putin in bid to reestablish Black Sea grain deal?
Here are some key things to know and what's at stake:
Where will the talks be held?
The meeting in Sochi on Russia's southern coast comes after weeks of speculation about when and where the two leaders might meet.
Erdogan previously said that Putin would travel to Turkey in August.
Why did Russia leave the grain deal?
The Kremlin refused to renew the grain agreement six weeks ago.
The deal – brokered by the United Nations and Turkey in July 2022 – had allowed nearly 33 million tonnes of grain and other commodities to leave three Ukrainian ports safely despite Russia's war.
However, Russia pulled out after claiming that a parallel deal promising to remove obstacles to Russian exports of food and fertiliser hadn't been honoured.
Moscow complained that restrictions on shipping and insurance hampered its agricultural trade, even though it has shipped record amounts of wheat since last year.
Why is Turkey a broker?
Since Putin withdrew from the initiative, Erdogan has repeatedly pledged to renew arrangements that helped avoid a food crisis in parts of Africa, the Middle East and Asia.
Ukraine and Russia are major suppliers of wheat, barley, sunflower oil and other goods that developing nations rely on.
The Turkish president has maintained close ties to Putin during the 18-month war in Ukraine.
Turkey hasn't joined Western sanctions against Russia following its invasion, emerging as a main trading partner and logistical hub for Russia's overseas trade.
NATO member Turkey, however, has also supported Ukraine, sending arms, meeting Ukrainian President Volodymyr Zelensky and backing Kyiv's bid to join NATO.
Russia-Turkey ties haven't always been rosy
Erdogan angered Moscow in July when he allowed five Ukrainian commanders to return home.
The soldiers had been captured by Russia and handed over to Turkey on condition they remain there for the duration of the war.
Putin and Erdogan – both authoritarian leaders who have been in power for more than two decades – are said to have a close rapport, fostered in the wake of a failed coup against Erdogan in 2016 when Putin was the first major leader to offer his support.
Traditional rivals Turkey and Russia grew closer over the following years as trade levels rose and they embarked on joint projects such as the Turkstream gas pipeline and Turkey's first nuclear power plant.
Ankara's relations with Moscow have frequently alarmed its Western allies.
The 2019 acquisition of Russian-made air defence missiles led to Washington kicking Turkey off the US-led F-35 stealth fighter programme.
Russia-Turkey relations in fields such as energy, defence, diplomacy, tourism and trade have flourished despite the countries being on opposing sides in conflicts in Syria, Libya and Nagorno-Karabakh.
Since Erdogan's reelection in May , Putin has faced domestic challenges that may make him appear a less reliable partner, most notably the short-lived armed rebellion declared by late mercenary chief Yevgeny Prigozhin in June.
What are Russia's demands?
The Sochi summit follows talks between the Russian and Turkish foreign ministers on Thursday, during which Russia handed over a list of actions that the West would have to take in order for Ukraine's Black Sea exports to resume.
Erdogan has indicated sympathy with Putin's position.
In July, he said Putin had "certain expectations from Western countries" over the Black Sea deal and that it was "crucial for these countries to take action in this regard".
UN Secretary-General António Guterres recently sent Russian Foreign Minister Sergey Lavrov "concrete proposals" aimed at getting Russian exports to global markets and allowing the resumption of the Black Sea initiative.
But Lavrov said Moscow wasn't satisfied with the letter.
Describing Turkey's "intense" efforts to revive the agreement, Turkish Foreign Minister Hakan Fidan said it was a "process that tries to better understand Russia's position and requests, and to meet them".
He added: "There are many issues ranging from financial transactions to insurance."