The Kremlin said on Tuesday that US President Donald Trump's recent statements, including a threat of sanctions on buyers of Russian exports, are serious and require analysis.

In a major policy shift underscoring his growing frustration with President Vladimir Putin, Trump on Monday announced new deliveries of weapons to Ukraine and warned that buyers of Russian exports could face sanctions unless Russia agrees to a peace deal on Ukraine.

Trump, who has said he wants to be remembered as a peacemaker, later told the BBC, referring to Putin: "I'm disappointed in him, but I'm not done with him. But I'm disappointed in him."

Asked about Trump's recent statements, Kremlin spokesman Dmitry Peskov said: "The US president's statements are very serious. Some of them are addressed personally to President Putin."

"We certainly need time to analyse what was said in Washington. And if and when President Putin deems it necessary, he will definitely comment."

Peskov continued, apparently referring to news of fresh weapons deliveries to Kyiv: "Decisions which are being made in Washington, in NATO countries, and squarely in Brussels, are perceived by the Ukrainian side not as a signal for peace, but as a signal to continue the war."

He reiterated that Russia was ready to continue direct negotiations with Ukraine and was still waiting for a signal from Kyiv on when the next talks could take place.