Ukraine is able to get weapons from the U.S. through several means, including Foreign Military Financing, which provides loans and grants for nations to buy weapons from U.S. defense companies, and the Ukraine Security Assistance Initiative, which allows the Pentagon to buy weapons for Kyiv but is currently out of funds. However, presidential drawdown authority, which allows the Defense Department to pull directly from its own stockpiles, has been the most significant tool for arming Ukraine. On Monday, the White House is holding a meeting to consider suspending shipments using the drawdown authority, a congressional aide and a second person familiar with the matter said.

https://www.wsj.com/politics/national-security/u-s-hitting-brakes-on-flow-of-arms-to-ukraine-980a71d1?page=1