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.

Russia now controls more than two-thirds of Ukraine’s Donetsk region — the main theater of the ground war. Russian forces have carved out a 10-mile-deep pocket around the Ukrainian troops defending the crucial city of Kostiantynivka, partly surrounding them from the east, south and west.