White House Press Secretary Karine Jean-Pierre said the assistance, which will be detailed later by the Pentagon, is expected to include Bradley infantry fighting vehicles, MRAPs and other personnel carriers, and self-propelled howitzers.
Washington and Berlin announced the previous day that they would provide armored vehicles -- Bradleys from the United States and Marders from Germany -- but did not provide details on numbers.
Bradleys, which are usually armed with a 25 mm autocannon, a 7.62 mm machine gun and anti-tank missiles, will provide Ukrainian forces with additional firepower.
"It's not a tank, but it's a tank killer," Pentagon spokesman Brigadier General Pat Ryder said Thursday.
"We're confident that it will aid them on the battlefield," he added.