US President Donald Trump said that Washington could quit talks to end the Ukraine war within days unless there is rapid progress from Moscow and Kiev.
The warning confirmed a sudden change of US messaging, with Secretary of State Marco Rubio earlier saying in Paris that the United States would "move on" if peace was not "doable."
"Yeah very shortly," Trump told reporters in the Oval Office when asked to confirm what Rubio had said about abandoning talks. "No specific number of days, but quickly. We want to get it done."
Top US officials gave mixed signals about the prospect of a Ukraine ceasefire on Friday, bringing uncertainty to the peace process just as Russia abandoned a moratorium on striking Ukrainian energy targets.
US Secretary of State Marco Rubio warned Washington would "move on" from peace talks unless it saw progress soon.
But speaking on a trip to Italy, US Vice President JD Vance said he was "optimistic" about ending the three-year war.
President Donald Trump has been pressing both Moscow and Kiev to agree a truce, but has failed to extract any major concessions from the Kremlin, despite repeated negotiations between his administration and Russia.
One of the few commitments Trump had wrangled from Russia -- a temporary moratorium on striking Ukrainian energy infrastructure -- "expired" on Friday, Kremlin spokesman Dmitry Peskov said in response to an AFP question.
Moscow has kept up strikes on Ukraine, killing at least two people and wounding dozens more in attacks on the northeastern regions of Kharkiv and Sumy, Ukrainian officials said.
After meeting European officials in Paris to discuss a ceasefire, Rubio said Washington needed to figure out soon whether a ceasefire was "doable in the short term".
"Because if it's not, then I think we're just going to move on," he told reporters.
Moments later, Vance said he did not want to prejudge the negotiations, but declared he was "optimistic" about the chances of peace.
Volodymyr Zelenskyy says no decision on the war’s resolution could be made without Kiev's direct participation.
'Good Friday' missiles
President Zelenskyy slammed the latest attacks on his country, which came just days before Easter.
Kiev earlier announced it had received the bodies of 909 soldiers from Russia.
"This is how Russia started Good Friday -- with ballistic missiles, cruise missiles, Shahed drones. A mockery of our people and cities," Zelenskyy said on Telegram.
Russia said it had hit "key drone production sites" and Ukrainian military airfields.
Since taking office, Trump has embarked on a rapprochement quest with the Kremlin that has alarmed Kiev and driven a wedge between the United States and its European allies.
Russian President Vladimir Putin last month rejected a joint US-Ukrainian proposal for a full and unconditional pause in the conflict, while the Kremlin has made a truce in the Black Sea conditional on the West lifting certain sanctions.
Trump has also repeatedly expressed anger and frustration at Zelenskyy in a marked break from policy under his predecessor, Joe Biden.
The United States is pushing Ukraine into a deal that would give Washington sweeping access to its mineral resources.
