The National Football League is conducting an internal audit of contracts between its teams and the U.S. Department of Defense and will refund the cost of any “paid patriotism” events at NFL games that used taxpayer money. The NFL took action after an investigation by U.S. Sens. Jeff Flake and John McCain, both Arizona Republicans, found the Department of Defense spent $6.8 million on events such as the pregame unfurling of giant American flags and color guard performances since 2012.

In the last four years, the Department of Defense paid 19 NFL teams more than $6 million. The Atlanta Falcons were paid $879,000, more than any other franchise, while the New England Patriots were paid $700,000. In all, the DOD has paid teams in the NFL, Major League Baseball, the National Hockey League, the National Basketball Association and Major League Soccer more than $10 million since 2012, the report said.

“With respect to more specific claims around recruitment funds being used for tribute activities, we are conducting an audit of all contracts between our clubs and the military service branches or state National Guard units,” NFL Commissioner Roger Goodell said in a letter to McCain and Flake, dated Tuesday, Nov. 2. “If we find that inappropriate payments were made, they will be refunded in full.”

The NFL is investigating team contracts with the DOD months after it told franchises that “any on-field recognition, community events, or other activities that are not specifically in the form of recruitment or advertising should never be included in contracts or otherwise performed for payment,” ESPN reported.

In the past, Department of Defense officials have asserted that on-field patriotic events are a recruiting tool for the United States’ armed forces. But Flake and McCain say there’s little evidence to back that up. “Although DOD has indicated the purpose of these contracts is to support recruiting, the Department doesn’t uniformly measure how and whether the activities under contract are actually contributing to recruiting,” the report said.