The Biden administration is planning to rush the last of over $6 billion remaining in Ukraine security assistance out the door by Inauguration Day, as the outgoing team prepares for the weapons flow to end once President-elect Donald Trump takes office.

The plan, described by two administration officials who were granted anonymity to discuss internal matters, is the only option the White House has to keep sending equipment to Ukraine to fight off continued Russian offensives. But the problems are immense. It normally takes months for munitions and equipment to get to Ukraine after an aid package is announced, so anything rolled out in the coming weeks would likely not fully arrive until well into the Trump administration, and the next commander in chief could halt the shipments before they're on the ground.

One big holdup to pushing that aid out the door quickly is that the U.S. can only send equipment already on its shelves. While the money allocated reimburses the Pentagon for that equipment, it is dependent on how fast new artillery shells and weapons can be produced or contracted to replace them.