US President Donald Trump says the ball is now in Russia's court on the American-proposed ceasefire in Ukraine. And the White House has revealed its negotiator is talking with Moscow about the plan.

The US and Ukraine wrapped up talks in Saudi Arabia on Tuesday, where they agreed to a 30-day ceasefire and the resumption of US military aid and intelligence sharing.

Speaking to reporters at the Oval Office, Trump said, "It's up to Russia now." He added that he received some positive answers from Moscow. But he noted that a positive message "means nothing" and that this is a very serious situation.

White House Press Secretary Karoline Leavitt said National Security Advisor Mike Waltz spoke with his Russian counterpart over the phone on Wednesday. She also said Trump's Mideast envoy, Steve Witkoff, would visit Moscow this week.

Ukrainian President Volodymyr Zelenskyy told reporters on Wednesday that if Russia agrees, it would pave the way for making plans to end the war.

Zelenskyy said: "The United States of America demonstrated its steps and position. Ukraine demonstrated and outlined its positions in a very direct way, without any reservations. And Russia will have to answer to that."

He added that everything depends on whether Russia wants a ceasefire, or to continue killing people.