President Joe Biden on Wednesday said the United States will send an additional $1 billion in military aid to Ukraine, the largest single tranche of weapons and equipment since the war began, in an effort to help stall Russia’s slow but steady march to conquer the eastern Donbas region.

The aid will include anti-ship missile launchers, howitzers and more rounds for the High Mobility Artillery Rocket Systems that the US forces are training Ukrainian troops on now – all key weapons systems that Ukrainian leaders have urgently requested.

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Biden also said the US will send $225 million more in humanitarian assistance to provide safe drinking water, medical supplies, food, health care, shelter and money for families to buy essential items.

The US remains committed, Biden said in a statement, “to supporting the Ukrainian people whose lives have been ripped apart by this war.”

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The aid comes as US Defence Secretary Lloyd Austin convened a meeting in Brussels of more than 45 nations to discuss support for Ukraine. At the start of the meeting, Austin warned that the West must step up weapons deliveries to Ukraine and prove its commitment to helping the country’s military fight along a 1,000-kilometre (620-mile) front line in a grinding war of attrition with Russia.

He urged the participating nations to demonstrate “our unwavering determination to get Ukraine the capabilities that it urgently needs to defend itself.” And he warned, “We can’t afford to let up and we can’t lose steam. The stakes are too high.”

Overall, since the war began in late February, the US has committed about $5.6 billion in security assistance to Ukraine, including this latest package.

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Officials said that about one-third of the latest $1 billion will be from presidential drawdown authority, which means the Pentagon will take weapons and equipment from it’s own stock and ship them to Ukraine. The remaining two-thirds would be equipment and weapons purchased from industry by the US and then transferred to Ukraine.

Austin’s meeting, also attended by Ukrainian Defence Minister Oleksii Reznikov, came on the opening day of a two-day gathering of NATO defence ministers at the alliance’s headquarters.

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Increased arms supplies can’t come too soon for the Ukrainian forces battling to keep Russia from taking control of their country’s industrial east after more than 3-and-a-half months of war.

In his nightly address to the nation, President Volodymyr Zelensky pleaded Tuesday for more and faster deliveries of Western arms, specifically asking for anti-missile defence systems.

“Allies are committed to continue providing the military equipment that Ukraine needs to prevail, including heavy weapons and long-range systems,” said Jens Stoltenberg, NATO secretary-general.

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Ukrainian Deputy Defence Minister Hanna Malyar said Tuesday that without help from the West, “we will not be able to win this war.’ She said Ukraine uses 5,000 to 6,000 artillery rounds a day, while Russia uses 10 times that many.

The defence ministers also planned to discuss moves to beef up forces along NATO’s eastern flank and elsewhere, which have gathered strength since Russia invaded Ukraine.