U.S. President Donald Trump and his Russian counterpart Vladimir Putin will not attend what could be the first direct peace talks between Moscow and Kyiv in three years on Thursday.

Putin on Sunday proposed direct negotiations with Ukraine in Turkey "without any preconditions," though he stopped short of saying he would attend. 

Late on Wednesday, the Kremlin said the delegation would include presidential adviser Vladimir Medinsky and Russian Deputy Defence Minister Alexander Fomin.

A U.S. official then said Trump would not attend — days after having said he was considering the trip.

The absence of the Russian and U.S. presidents lowers the expectations for a major breakthrough in the war that Russia started in February 2022.

Ukrainian President Volodymyr Zelenskyy had challenged Putin to attend the talks "if he's not afraid," in an apparent contest to show Trump who wants peace more.

Zelenskyy was on his way to Turkey, a Ukrainian official said Wednesday. Earlier, Zelenskyy had said he would take part in the negotiations only if Putin were there.

Trump wants the two sides to sign up to a 30-day ceasefire to pause Europe's biggest land war since the Second World War, and a Russian lawmaker said on Wednesday there could also be discussions about a huge prisoner of war exchange.

Zelenskyy backs an immediate 30-day ceasefire, but Putin has said he first wants to start talks at which the details of such a ceasefire could be discussed.

Threat of more sanctions

Trump, who is growing increasingly frustrated with both Russia and Ukraine as he tries to push them toward a peace settlement, said he was "always considering" secondary sanctions against Moscow if he thought it was blocking the process.

U.S. officials have spoken about possible financial sanctions and secondary sanctions on buyers of Russian oil. Western European leaders have also threatened Russia with further sanctions if there is no progress in halting the fighting in Ukraine.

A Ukrainian diplomatic source told Reuters on Wednesday that Ukraine's leadership would decide on its next steps for peace talks in Turkey once there was clarity on Putin's participation.

U.S. Rep. Jim Himes told CNN that he saw no reason for Trump — or Zelenskyy — to be in Turkey if Putin would not be going.

"I think everybody understands that Putin is not interested in real peace negotiations," said Himes, the ranking Democrat on the U.S. House of Representatives' intelligence committee.

The Democrat said "the real question" now is how Trump should adjust the U.S. stance on Russia.

Before returning to the Oval Office, Trump had, on multiple occasions, claimed that he could end the war in 24 hours. More than three months into his new presidency, the war continues.

The war, which recently crossed the three-year mark, has seen the use of trenches and tanks, as well as the extensive use of drones by both sides.

The UN says at least 12,700 civilians have been killed and more than 30,000 others have been injured, since Russia launched its full-scale invasion of its neighbour.