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.

This winter, he tried to humiliate Ukraine's president, and now allows arms transfers to Kyiv. Behind the dramatic shift in Trump's thinking.

President Donald Trump is downplaying the possibility of sending Ukraine long-range weapons as Kyiv awaits an injection of U.S. weaponry that it hopes will help it beat back an intensifying Russian air offensive.