The United States will give USD 325 million in new security assistance to Ukraine, President Joe Biden has announced as he hosted his Ukrainian counterpart Volodymyr Zelenskyy at the White House and vowed to defend the war-struck country from Russian aggression.

The White House meeting on Thursday was the sixth in-person meeting between the two leaders.

"Mr. President, the brave people of Ukraine -- and that's not hyperbole; the people of Ukraine have shown enormous bravery and have inspired the world with their determination to defend these principles," Biden told Zelenskyy in the Oval Office of the White House.

"Together with our partners and allies, the American people are determined to see to it that we do all we can to ensure the world stands with you, and that is our overwhelming objective right now," he said, welcoming the Ukrainian leader for the third time at the White House this year.\

"Our regular dialogue has proved that our countries are really, truly allies and strategic friends. And we greatly appreciate the vital assistance provided by the United States to Ukraine to combat Russian terror," Zelenskyy said.

Reiterating his pledge to defend Ukraine's sovereignty, Biden said during the bilateral meeting later that the US will continue to support Ukraine's diplomatic effort to deliver a just and lasting peace that protects its sovereignty and territorial integrity.

"Russia alone stands in the way of peace. It could end today. Instead, Russia is seeking more weapons from Iran and North Korea. It would violate multiple UN Security Council resolutions that Moscow itself voted to put in place," he said.

Biden announced the next tranche of US security assistance worth USD 325 million to Ukraine, including more artillery, ammunition, and anti-tank weapons. "And next week, the first US Abrams tanks will be delivered to Ukraine," he said.\

The two leaders also reached a new agreement to strengthen Ukraine's defence capabilities, under which Washington will help Kyiv improve its air defence during the winter season to help protect its people.\

"We also focused on strengthening Ukraine's air defence capabilities to protect the critical infrastructure that provides heat and light during the coldest and darkest days of the year. That includes providing a second HAWK air defence battery with steady deliveries of additional HAWK and other systems each month through the winter. A new package of launchers and interceptors that's going to protect Ukraine -- Ukraine's grain silos, hospitals, schools, and power plants," Biden said.

"These capabilities will help Ukraine harden its defences ahead of what is likely to be a tough winter filled with renewed Russian attacks on Ukrainian critical infrastructure to try to deprive innocent people of necessities like heat and electricity," he said.

"Because President Putin cannot achieve his objectives on the battlefield, he has reduced to and is resorting to attacks that are intended to plunge ordinary people's lives into cold and darkness. We are going to do everything --working with Ukrainians to make that task more and more difficult for Russia to be able to pull off," he added.

Later, Zelenskyy told reporters that during the meeting, the two leaders agreed to work on the future force of Ukraine. Russia launched a "special military operation" against Ukraine in February last year.

"It's very important. It is a strategic decision that will allow us to prevent any new aggression against us, against Ukraine, and our people. And this will be one of the outcomes of the Vilnius G7 Declaration and our bilateral security arrangements," he said.

US National Security Advisor Jake Sullivan said that the meeting between Biden and Zelenskyy came at a "significant" moment.

"This meeting comes at a significant moment, as Ukrainian forces continue to make progress in their counteroffensive, and just after Russia launched yet another brutal wave of airstrikes against five cities -- five cities in Ukraine that hit critical civilian infrastructure and knocked out power for many people in many different parts of the country," Sullivan said at a news conference.

The package announced by the US includes weapons and equipment to help Ukraine maintain its momentum in the counteroffensive. It contains additional ammunition for US-provided HIMARS systems, anti-armour capabilities, artillery, ammunition, and more DPICMs (Dual-purpose improved conventional munition), which have helped Ukraine make gains and helped Ukraine defend against counterattacks.