S. 4649 proposes a change to the Mutual Security Act of 1954 regarding the United States' membership in NATO. If all NATO countries agree to let Ukraine start the process of joining NATO, this bill would give the United States a reason to immediately withdraw from the North...
Simple Explanation
If NATO countries agree that Ukraine can join, this bill says the U.S. could decide to leave the group because of a rule that lets them do so.