The $6 billion package — the largest the US has announced — is under the Ukraine Security Assistance Initiative (USAI). USAI is different from than the PDA package in that it contracts with the US defense industry to purchase new equipment, whereas PDAs pull equipment from existing US stocks.

The U.S. has announced a new $400 million package of military aid for Ukraine WASHINGTON -- The U.S. announced a new $400 million package of military aid for Ukraine on Friday, as Kyiv struggles to hold off advances by Russian troops in the northeast Kharkiv region.

U.S. President Joe Biden on May 10 authorized a $400 million defense aid package for Ukraine, according to a statement on the White House's website.