The N.F.L. said that any of its teams found to have been paid by a branch of the military for promotional purposes would have to return the money.
In a letter to Senators John McCain and Jeff Flake, both Republicans from Arizona, Commissioner Roger Goodell said that the league was conducting an audit of all contracts between the league’s 32 teams and various branches of the military.
“We strongly oppose the use of recruitment funds for anything other than their proper purpose,” Goodell wrote in a letter to the senators. “If we find that inappropriate payments were made, they will be refunded in full.