Unlike other Biden nominees who also may face skeptical confirmation hearings or tight votes in a closely divided Senate, Austin is likely to run into trouble aside from ideological positions or previous statements that may come up. Instead, it‘s the fact that he‘s only been retired from active duty for four years.

Civilian control is a key aspect of the U.S. military, and to underscore that principle, defense secretaries are legally required to have been retired from active duty for at least seven years.