By Darya Tarasova, Daria Tarasova-Markina, Edward Upright and Sana Noor Haq, CNN

(CNN) — Russian President Vladimir Putin on Monday declared a unilateral three-day ceasefire in Ukraine next month, a move met with skepticism by Ukrainian officials who demanded the Kremlin leader immediately accept a longer truce proposal from the United States that he has so far rejected.

Moscow said “all military actions” in Ukraine would be suspended from midnight May 8 to midnight May 11, a decision which it said was based on “humanitarian considerations.” The truce would coincide with Russia’s World War II Victory Day commemorations on May 9 and the 80th anniversary of the defeat of Nazi Germany.

Putin’s announcement comes as the Trump administration ramps up pressure on Moscow and Kyiv to agree to a deal to end the war. On Sunday, US Secretary of State Marco Rubio said this week would be “very critical” in determining whether the US would persist with its efforts to broker peace.

In early March, Ukrainian President Volodymyr Zelensky accepted a US-led proposal for a 30-day ceasefire, but Putin has repeatedly declined to follow suit.

“If Russia truly wants peace, it must cease fire immediately,” Ukrainian Foreign Minister Andrii Sybiha said in response to Monday’s announcement from the Kremlin. “Why wait until May 8th?”

“Ukraine is ready to support a lasting, durable, and full ceasefire. And this is what we are constantly proposing, for at least 30 days,” he added.

‘No ceasefire in reality’

The announcement came a little more than a week after the Kremlin proclaimed a 30-hour truce over Easter, which Kyiv cautiously agreed to. Ukraine’s military later accused Russia of violating that April 19 ceasefire with more than 2,900 attacks along the expansive frontlines. Moscow also accused Ukraine of repeatedly breaking that truce.

Between April 19 and April 28, at least 62 civilians were killed in Ukraine and another 290 people injured, according to a CNN tally of figures from local authorities and emergency services.

Senior Trump administration officials say the coming weeks will be a pivotal time in negotiating an end to the war, more than three years after Russia launched its full-scale invasion of Ukraine.

“We’re close, but we’re not close enough,” Rubio said on NBC’s “Meet the Press” on Sunday, following a phone call with Russia’s Foreign Minster Sergey Lavrov.

Moscow described a “productive exchange of views” between the two.

US President Donald Trump has voiced increasing frustration over the failed efforts to broker a peace agreement within his self-imposed target of the first 100 days of his presidency. On Sunday, Trump leveled pointed criticism at Putin in some of his most potent comments to date, urging his Russian counterpart to “stop shooting, sit down and sign a deal.”

“We have the confines of a deal, I believe, and I want him to sign it and be done with it and just go back to life,” Trump said.

Trump’s comments came after he returned to Washington following a trip to Pope Francis’ funeral at the Vatican on Saturday. He met Zelensky on the sidelines of the ceremony for a short talk that both sides described as productive.

This story has been updated with additional developments.