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.

The Kremlin said on Friday that it did not believe that a tougher stance U.S. President Donald Trump has adopted towards Russia over its war in Ukraine means the end of U.S-Russia talks aimed at reviving their battered ties.

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.