Thompson, whom the Redskins drafted in the seventh round out of Boise State, had appeared in two games and recorded two tackles this season. His agent didn’t immediately respond to a message left for him.
If he clears waivers, he is likely to be brought back as a member of Washington’s practice squad.
Buchanon had missed the first four games of the season while serving a suspension for violating the league’s substance abuse policy. He went through his first practice of the regular season on Tuesday, and Redskins coach Mike Shanahan said that the 10th-year veteran could help the Redskins right away.