U.S. President Donald Trump's decision to ramp up arms shipments to Ukraine is a signal to Kyiv to abandon peace efforts, Russia said on Thursday, vowing it would not accept the "blackmail" of Washington's new sanctions ultimatum.

Ukraine has proposed a new round of peace talks with Russia, President Volodymyr Zelensky has said, in a move aimed at restarting negotiations that halted last month. Senior security official Rustem Umerov has offered to meet the Russian side next week, Zelensky said in his evening address, adding that everything had to be done to get a ceasefire.

In the days since President Donald Trump issued a 50-day ultimatum to Russian President Vladimir Putin to end the war in Ukraine, Kremlin officials have shown little interest in coming to the negotiating table.

Russian media have been reacting to Trump's growing criticism of Putin, the most recent being on Tuesday when he accused the Russian leader of peddling "bulls***" over his intentions in Ukraine, after rejecting U.S. ceasefire proposals.

In a major shift toward Ukraine, Trump announces a plan to send weapons, including Patriot systems, and threatens 100 percent tariffs if Russia doesn’t reach a deal soon.

Russian strikes killed three people across Ukraine on Saturday, authorities said, while Moscow had to briefly suspend trains in its southern Rostov region after an overnight drone attack by Kyiv.