The Nationals placed Beeter on the 15-day injured list Sunday, retroactive to April 23, due to right forearm soreness.
It's unclear when exactly the right-hander suffered the injury, but he hasn't seen the field since firing a scoreless frame against Atlanta last Tuesday. Beeter and Gus Varland lead the Nationals with two saves each, so Varland is likely to be the primary option at closer while Beeter is sidelined.