WARSAW, Poland (AP) — The U.K. on Tuesday pledged an additional $620 million in new military supplies for Ukraine, including long-range missiles and four millions rounds of ammunition, at a time when Ukraine is struggling to hold off advancing Russian forces on the eastern front line of the war, now in its third year.

British Prime Minister Rishi Sunak spoke with Ukraine’s President Volodymyr Zelenskyy on Tuesday morning to confirm the assistance and “assure him of the U.K.’s steadfast support for Ukraine’s defense against Russia’s brutal and expansionist ambitions,” Sunak’s office said.

Sunak was traveling to Warsaw later Tuesday to meet with Polish Prime Minister Donald Tusk and NATO Secretary General Jens Stoltenberg for talks about further aid for Ukraine.

Ahead of the visit the U.K. government said Sunak would announce 500 million pounds ($620 million, 580 million euros) in new British military supplies, including 400 vehicles, 60 boats, 1,600 munitions and 4 million rounds of ammunition. The shipment will include British Storm Shadow long-range missiles, which have a range of some 150 miles and have proved effective at hitting Russian targets.