When Toby Keith stepped onstage to perform at the ACM Salute to the Troops event on Monday (April 7), he didn't realize he was actually the recipient of an award.

At the end of the more than three-hour program, the country star performed his final song, 'American Soldier,' and shook the hands with all the military personnel standing onstage. Then, Keith got a big surprise.

An executive with the USO took the microphone and announced Keith had played 200 shows and entertained more than 250,000 military men, women, and their families. He'd earned the Spirit of the USO Award.

“That caught me off guard,” the singer said, according to the Tennessean. “I saw a need and a void the great Bob Hope left behind, and no one was filling it, but as hard as Big Dog Daddy tried, I couldn’t bring Marilyn Monroe.”

The ACM Salute to the Troops was a smashing success, with an all-star lineup of performers that honored military men and women for their sacrifices and service. Fans can watch ‘ACM Presents: An All-Star Tribute to the Troops’ on CBS on May 20.