The US announced on Wednesday a $1.1 billion package of military equipment, including another 18 High Mobility Artillery Rocket Systems, to increase Ukraine's defences against Russia's invasion.
The Pentagon's announcement is part of a broader shift within the White House to focus on Kyiv's long-term needs as its war against Moscow drags past seven months.
“We will not be deterred from supporting Ukraine,” White House press secretary Karine Jean-Pierre said.
"We will continue to stand with the Ukrainian people and provide them with the security assistance they need to defend themselves, for as long as it takes."
US officials have previously hailed the capabilities of the Himars, which have been critical in Ukraine's counter-offensive operations. The Pentagon has provided 34 of them.
Included in the Pentagon's latest transfer from its stocks are more ammunition for the Himars, hundreds of armoured and tactical vehicles, communications and surveillance equipment, various radars and military gear.
It also includes funding for equipment to detect explosives, and to maintain and sustain the equipment provided.
President Joe Biden has often used the Pentagon's transfer capabilities to provide weapons to Ukraine with greater speed.
The US has committed $16.2bn in military assistance to Ukraine since Russia's invasion on February 24, the Pentagon said.
Ukrainian President Volodymyr Zelenskyy praised the Pentagon's announcement as a “very timely decision showing that Russian blackmail does not work”.
Mr Zelenskyy has been urging Kyiv's allies to put pressure on Moscow for what he calls “nuclear blackmail” as Russian President Vladimir Putin said his threat of using nuclear weapons was “not a bluff”.