ISTANBUL, Turkey (AFP) — United States and Russian officials met Friday at an Istanbul hotel on the sidelines of Ukraine talks being led by Turkey, a US official said.

Michael Anton, the director of policy planning at the State Department, began closed-door talks with Vladimir Medinsky, a hawkish Kremlin aide sent to lead the discussions with Ukraine after Russian President Vladimir Putin declined to take part.

US Secretary of State Marco Rubio called Friday for an end to the bloodshed in Ukraine.

The Kremlin said Friday that a meeting between Donald Trump and Putin over Ukraine was “undoubtedly necessary,” after the US president said nothing would be resolved until the two leaders met.

“Contacts between presidents Putin and Trump are extremely important in the context of the Ukrainian settlement,” Kremlin spokesperson Dmitry Peskov told reporters, adding that “a meeting is undoubtedly necessary.”

Meanwhile, North Atlantic Treaty Organization (NATO) chief Mark Rutte said Putin had made a “big mistake” sending a lower-rank delegation to conduct Friday’s first direct peace talks with Ukraine in three years.

Expectations for the talks — initially proposed by Putin — sank after the Russian leader declined Ukrainian President Volodymyr Zelensky’s call to meet at the presidential level in Turkey.

“He knows extremely well that the ball is in his court, that he is in trouble, that he made a big mistake by sending this low-level delegation,” Rutte told reporters in Tirana, at a meeting of European leaders who were expected to close ranks around Zelensky.

“I think all the pressure is now on Putin,” said Rutte. “The ball is clearly in his part of the field now, in his court,” said Rutte. “He has to play ball. He has to be serious about wanting peace.”

Russian and Ukrainian delegations will hold their first talks in more than three years of war, with tens of thousands killed in Europe’s worst conflict since World War II.

Kyiv is seeking an “unconditional ceasefire” at the talks, while Moscow says it wants to address the “root causes” of the conflict and revive failed 2022 negotiations in which it made sweeping territorial and political demands of Ukraine.

Expectations of a breakthrough are slim, with the two sides having spent the last 24 hours slinging insults at each other and Zelensky accusing Moscow of not being “serious” about peace.