The NFL has issued another strong warning to coaches who won't wear masks on the sideline during games.

The league is threatening suspensions and forfeiture of draft picks as punishment for failing to comply with COVID-19 game-day protocols, according to a league memo.

The memo, which was sent to coaches, general managers and team executives by NFL executive vice president Troy Vincent, includes a passage in which the NFL says it will "address lack of compliance with accountability measures that may include ... suspensions and/or forfeiture of draft picks."

It's the second time this season that the NFL has warned coaches to comply with coronavirus-related protocols by wearing a mask on the sideline.