3/27/2012 - Col. Patrick McKenzie, the 51st Fighter Wing commander, shakes hands with President Barack Obama at Osan Air Base, South Korea, March 25, 2012, during introductions by Gen. James Thurman, the U.S. Forces Korea commander. The president transited the base on his way to the 2012 Nuclear Security Summit in Seoul, South Korea. (U.S. Air Force photo/Senior Airman Adam Grant)

3/27/2012 - President Barack Obama waves as he exits Air Force One during his arrival at Osan Air Base, South Korea, March 25, 2012. The president transited the base on his way to the 2012 Nuclear Security Summit in Seoul, South Korea. (U.S. Air Force photo/Airman 1st Class Michael Battles)

3/27/2012 - Gen. James Thurman, the U.S. Forces Korea commander, greets President Barack Obama at Osan Air Base, South Korea, March 25, 2012. The president flew to the base on Air Force One on his way to the Nuclear Security Summit in Seoul, South Korea. (U.S. Air Force photo/Senior Airman Adam Grant)