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.

Trump said the United States would put secondary tariffs on countries that do business with Russia if a peace deal is not reached in 50 days.

Russia launched four missiles and 136 drones into Ukraine overnight into Monday morning, according to Ukraine's air force.