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Celebrities have a long tradition of entertaining troops. Actress and comedian Kathy Griffin (r.) and singer Katy Perry perform during the VH1 Divas Salute The Troops presented by the USO show at Marine Corps Air Station Miramar in San Diego on Dec. 3, 2010. Zuma Press/Newscom/File
Musician Billy Ray Cyrus (c.) performs at the 2009 USO Holiday Tour stop in Kandahar, Afghanistan, on Dec. 17, 2009. Chad J. McNeeley/DOD/Sipa Press/Newscom/File
Actor Bob Hope entertains troops with the USO on the island of New Georgia in the Solomons in 1944. Bettman-UPI Photo/Reuters/File
Singer Wayne Newton signs autographs for troops on an Independence Day tour to Korea on July 14, 2009. Dave Gatley/PRNewsFoto/Newscom/File
Actor Robin Williams (r.) and US Chairman of Joint Chiefs of Staff Admiral Michael Mullen throw footballs to ISAF troops during a 'Holiday Troop Visit' by US celebrities at Kandahar Air Field in Afghanistan on Dec. 16, 2010. Behrouz Mehri/AFP/Getty Images/Newscom/File
Actress Marilyn Monroe sings for troops in Korea in 1954.
Actor D.B. Sweeney and former All-Pro NFL running back Warrick Dunn sign autographs onboard the USS Ronald Reagan underway in the Gulf of Oman on July 13, 2009. Chad J. McNeeley/DOD/Sipa Press/Newscom/File
Bing Crosby, stage, screen, and radio star, sings to Allied troops at the opening of the London stage door canteen in Piccadilly, London, in 1944. Edisto Images/Newscom/File
Actress and singer Marlene Dietrich signs the plaster cast of an injured soldier in a US army hospital in Belgium in 1944. AKG Photos/Newscom/File
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