Editor's note: The article was updated with a response from U.S. Special Envoy Keith Kellogg.
U.S. President Donald Trump is weighing new sanctions on Russia after a deadly weekend of missile and drone strikes across Ukraine, as Moscow delays delivering a promised peace proposal.
During a phone call with Russian President Vladimir Putin on May 19, Trump was told that a "memorandum of peace" outlining conditions for a ceasefire would be delivered shortly. As of May 27, no such document has been received, a U.S. official and a White House source familiar with the matter told CNN.
Kremlin spokesperson Dmitry Peskov said earlier that there was "no timeline" for completing the document, according to Russian state media TASS.
"He’s killing a lot of people," Trump said of Putin on May 25. "I don’t know what’s wrong with him. What the hell happened to him?" The president's comments came amid mounting pressure from both parties in Congress to take a firmer stance.
More than 80 senators have backed a bipartisan bill seeking sweeping new measures, including secondary sanctions and 500% tariffs on nations purchasing Russian energy. "All of us, by our public statements as well as private contacts, are pressing very, very hard," Democratic Senator Richard Blumenthal told CNN.
On Truth Social, Trump warned that Russia is "playing with fire" and hinted at potential consequences: "What Vladimir Putin doesn’t realize is that if it weren’t for me, lots of really bad things would have already happened to Russia, and I mean REALLY BAD."
The remarks prompted a pointed reaction from Moscow, with former Russian President Dmitry Medvedev interpreting them as a warning of possible escalation.
"Regarding Trump's words about Putin 'playing with fire' and 'really bad things' happening to Russia. I only know of one really bad thing — WWIII," Medvedev wrote on X on May 27. "I hope Trump understands this!"
U.S. Special Envoy for Ukraine Keith Kellogg hit back at Medvedev for his remarks, calling them "reckless" and "unfitting of a world power."
"President Trump... is working to stop this war and end the killing. We await receipt of (the Russian) Memorandum... that you promised a week ago. Cease fire now," Kellogg said on X.
According to Secretary of State Marco Rubio, Russian Foreign Minister Sergey Lavrov told him ahead of the Trump-Putin call that Moscow would prepare a draft outlining its requirements for a ceasefire. Russian Foreign Ministry spokesperson Maria Zakharova confirmed on May 27 that work on the document is ongoing. "As soon as the memorandum is prepared, it will be handed over to Kyiv," she said.
