The package of $1 billion worth of arms includes more artillery, coastal anti-ship defense systems and ammunition for artillery and advanced rocket systems that Ukraine is already using, Biden said.

In the phone call with Zelensky, Biden said he "reaffirmed my commitment that the United States will stand by Ukraine as it defends its democracy and support its sovereignty and territorial integrity in the face of unprovoked Russian aggression," according to a US statement.

Biden also announced $225 million worth of humanitarian assistance for Ukraine.

The money will go toward supplying food, drinking water, medical supplies and other critical goods.

"The bravery, resilience, and determination of the Ukrainian people continues to inspire the world," Biden said.

The Pentagon detailed the new supplies as including 18 more 155mm howitzers and 36,000 rounds of ammunition for them; two land-based Harpoon anti-ship missile systems; and additional rockets for the four Himars precision rocket systems that Ukraine is soon to put in the field.

With ranges of up to around 80 kilometers (50 miles), the Himars rockets potentially give Ukraine a greater ability to attack Russian targets, with greater precision, in the ongoing artillery battle along the front lines.

US officials said that the first batch of Ukrainian troops were completing training on the Himars on Wednesday.

Also in the new package are thousands of secure radio and night vision devices and thermal sighting systems, the Pentagon said.

This package takes to $5.6 billion the value of arms the United States has provided Ukraine since Russia invaded on February 24.