The United States has authorised an additional $400m (£330m) in military aid to Ukraine, including weapons, munitions and air defence equipment

"The artillery ammunition, precision fires, air defence missiles, and tactical vehicles that we are providing will best serve Ukraine on the battlefield," he said.

The deal will include more than 200 generators to help Ukraine deal with power outages caused by Russia's attacks on energy infrastructure.

They are "intended to support both civilian and military power needs" and are aimed at easing pressure on the grid, said Pentagon Press Secretary Brigadier General Pat Ryder.