Russian and Ukrainian officials arrived at a palace in Istanbul on Monday for their second round of direct peace talks since 2022, with no sign they are any closer to an agreement, one day after Kyiv struck some of Moscow's nuclear-capable bombers.

The two sides are expected to discuss their respective ideas for what a full ceasefire and a longer-term path to peace should look like amid stark disagreements and pressure from US President Donald Trump, who has warned the US could abandon its role as a mediator if there's no progress.

The Russian and Ukrainian delegations arrived at Istanbul's sumptuous Ciragan Palace by the Bosphorus, along with senior Turkish officials, though there was an unexplained delay in the start of talks, which had been slated to start at 10 GMT.

Vladimir Medinsky, the head of Moscow's delegation, said that Russia had received Ukraine's draft memorandum for a peace accord ahead of the talks. Russia has said it will present its own draft peace accord at the talks, along with unspecified ceasefire proposals. Ukrainian Defence Minister Rustem Umerov is heading the Ukrainian delegation.

Their last round of talks in Istanbul on May 16 yielded the biggest prisoner swap of the war, with each side freeing 1,000 prisoners, but no sign of peace, or even a ceasefire, as both sides merely stated their opening negotiating positions.

Ukrainian President Volodymyr Zelenskiy, in Lithuania for talks, said on Monday that ceasefire and humanitarian issues, such as returning more prisoners from Russia, would be a priority for Kyiv at the Istanbul talks.

Ukraine regards Russia's approach to date as an attempt to force it to capitulate - something it says it will never do - while Moscow, which advanced on the battlefield in May at its fastest rate in six months, says Kyiv should submit to peace on Russian terms or face losing more territory.

Amid low expectations of a breakthrough, a Ukrainian source told Reuters ahead of Monday's talks that Kyiv was ready to take real steps towards peace if Moscow showed flexibility and what they described as a readiness to "move forward, not just repeat the same previous ultimatums."

The mood in Russia before the talks was angry, with influential war bloggers calling on Moscow to deliver a fearsome retaliatory blow against Kyiv after Ukraine on Sunday launched one of its most ambitious attacks of the war, targeting Russian nuclear-capable long-range bombers in Siberia and elsewhere.

Ukraine's air force said Russia had launched 472 drones at Ukraine, the highest nightly total of the war.

Russia's Moskovsky Komsomolets newspaper cited Vasily Stoyakin, a political analyst, as saying it was hard to imagine the Istanbul talks producing much given how far apart the two sides were.

"It's some kind of theatre of the absurd going on in Istanbul right now. The two sides are going to discuss completely different agendas," it cited Stoyakin as saying.