MOSCOW -- Russian President Vladimir Putin supports the position of US President Donald Trump on a settlement of the conflict in Ukraine, but has concerns over remaining unresolved issues, Kremlin spokesman Dmitry Peskov said on Friday.

"So, indeed, there is a lot that needs to be done, but, nevertheless, the president expressed solidarity with Mr. Trump's position," the spokesman said, adding that there were grounds for "cautious optimism" regarding a settlement of the conflict.

Peskov confirmed that the Russian president held talks with US special envoy Steve Witkoff late on Thursday, adding that once the US diplomat shared remaining details with Trump, it would be possible to determine a potential time for the two presidents to talk.

During a press briefing on Thursday, Putin said Russia is "in favor" of the 30-day ceasefire plan proposed by the United States and Ukraine, but that nuances exist.

Trump said later on Thursday that he saw "good signals" toward finalizing the ceasefire agreement between Russia and Ukraine.