The NFL owners have approved a new national anthem that requires players to stand if they are on the field but they have the option to remain in the locker room if they prefer.
Jed York of the 49ers abstained from the vote.
The policy subjects teams to a fine if a player or any other team personnel do not stand for the anthem. That includes any attempt to sit or kneel, as dozens of players have done during the past two seasons.
"This season, all league and team personnel shall stand and show respect for the flag and the Anthem," NFL commissioner Roger Goodell said in a statement. "Personnel who choose not to stand for the Anthem may stay in the locker room until after the Anthem has been performed.
"We believe today's decision will keep our focus on the game and the extraordinary athletes who play it -- and on our fans who enjoy it."