U.S. Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff concludes the 2010 USO Holiday Tour at Andrews Air Force Base, Maryland on Dec.18, 2010. Mullen and his wife Deborah are hosting the holiday tour featuring comedians Robin Williams, Lewis Black and Kathleen Madigan, Tour de France champion Lance Armstrong and country musicians Kix Brooks and Bob Dipiero touring the Central Command area of responsibility. (DoD photo by Mass Communciation Specialist 1st Class Chad J. McNeeley/Released)

Comedian Robin Williams visits with U.S. Army Lt. Gen. John F. Campbell, commanding general, Combined Task Force 101 aftter the USO Holiday Tour show at Bagram Air Field, Afghanistan on Dec.15, 2010. U.S. Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff and his wife Deborah are hosting the holiday tour featuring Willaims and comedians Robin Williams, Lewis Black and Kathleen Madigan, Tour de France champion Lance Armstrong and country musicians Kix Brooks and Bob Dipiero touring the Central Command area of responsibility. (DoD photo by Mass Communciation Specialist 1st Class Chad J. McNeeley/Released)

Robin Williams, Lance Armstrong. Photo US Embassy Kabul.

BAGRAM AIRFIELD, Afghanistan -- Comedian/actor Robin Williams performs for servicemembers deployed here Dec. 15 as part of a United Service Organizations Inc. tour. Other entertainers included Kathleen Madigan, Lance Armstrong, Lewis Black, and Kix Brooks.

Robin Williams. Photo US Embassy Kabul.

Songwriter Bob Dipiero, left, and country music artist Kix Brooks, of Brooks & Dunn, perform for U.S. Marines with 2nd Battalion, 6th Marine Regiment at Camp Hanson in Helmand province, Afghanistan, Dec. 16, 2010. Dipiero and Brooks were part of the annual USO holiday tour, which was hosted by Chairman of the Joint Chiefs of Staff Navy Adm. Mike Mullen and also featured appearances by comedians Robin Williams, Lewis Black and Kathleen Madigan and Tour de France champion Lance Armstrong. (DoD photo by Mass Communication Specialist 1st Class Chad J. McNeeley, U.S. Navy/Released)

Lance Armstrong. Photo US Embassy Kabul.

Robin Williams. Photo US Embassy Kabul.

Lance Armstrong and Lewis Black. Photo US Embassy Kabul.

Photo US Embassy Kabul.

Lewis Black. Photo US Embassy Kabul.

Kix Brooks. Photo US Embassy Kabul.

KANDAHAR, Afghanistan — Seven-time Tour de France winner, Lance Armstrong, takes a picture with Servicemembers during the USO’s annual holiday tour, Dec. 16, 2010. (U.S. Army Corps of Engineers photo by Mark Abueg)

U.S. Navy Adm. Mike Mullen, chairman of the Joint Chiefs of Staff concludes the 2010 USO Holiday Tour at Andrews Air Force Base, Maryland on Dec.18, 2010. Mullen and his wife Deborah are hosting the holiday tour featuring comedians Robin Williams, Lewis Black and Kathleen Madigan, Tour de France champion Lance Armstrong and country musicians Kix Brooks and Bob Dipiero touring the Central Command area of responsibility. (DoD photo by Mass Communciation Specialist 1st Class Chad J. McNeeley/Released)