The US on Friday announced a $400 million military aid package for Ukraine, as Kyiv tries to stop advances by Russian troops in the Kharkiv region.
White House national security spokesman John Kirby said President Joe Biden's administration has been working to get Ukraine the weapons systems that it needs to defend itself against Russia's intensified attacks.
“We are confident in the Ukrainian armed forces and we are working around the clock to get them the equipment, the tools and the weapons that they need to defend against these attacks,” Mr Kirby said.
“No one should underestimate the Ukrainian people and no one should underestimate President Biden's commitment and resolve to standing with Ukraine.”
Mr Kirby said it is likely that Russia will increase the intensity of its attacks over the coming weeks and send additional troops to the north-eastern region of Kharkiv in an attempt to establish a shallow buffer zone along the Ukrainian border.
But the US does not expect any major breakthroughs, he added.
The latest tranche of aid, Mr Kirby said, includes additional artillery ammunition, interceptors and anti-aircraft missiles, armoured vehicles, artillery rounds, anti-armour systems and other weapons and equipment.
In late April, the US Congress passed a supplemental funding that included $60 billion in aid for Ukraine.
Mr Biden announced $1 billion in weapons through his drawdown authority. Days later, the Pentagon announced a $6 billion military package, its biggest yet for Kyiv.
Ukraine-Russia conflict latest – in pictures
