Gen. Walter "Skip" Sharp replaced Gen. Burwell Bell in 2008 as the USFK commander.

The U.S. stations about 28,500 troops in South Korea as a legacy of the 1950-53 Korean War.

A native of Marietta, Oklahoma, Thurman served as deputy chief of staff, commanding general of U.S. V Corps in Heidelberg, Germany, before assuming his current assignment in June 2010.

He received a bachelor's degree in history from East Central University and a master's in management from Webster University.

In making Gen. Thurman's and several other personnel announcements, Gates described the nature of the ongoing joint military drills with South Korea.

"This is part of a series of exercises that go on all the time between U.S. and Republic of Korea forces," the chief defense official said. "They are part of a program of making sure that we have the capabilities and we have the skills to be able to respond to various contingencies. We've seen over the last year provocations by the North that make the importance of these exercises, I think, even more clear."

North Korea has renewed its threat to wage nuclear war and vowed to respond militarily to the 11-day South Korean-U.S. military exercise called Key Resolve/Foal Eagle that began Monday.

Speaking to reporters, State Department spokesman Philip Crowley said Monday the exercises are defensive in nature.

"The U.S. and Republic of Korea routinely conduct joint military exercises," Crowley said. "North Korea was notified about these exercises on February 14th, and its belligerent rhetoric is unwarranted. (Yonhap News)