Fort Riley ? Lt. Col. James J. Walton, 41, died of wounds received Saturday in Kandahar, Afghanistan, when the vehicle in which he was traveling struck a homemade bomb and encountered small arms fire, Fort Riley officials announced Tuesday.

Walton, of Rockville, Md., was an aviation officer serving on a military transition team assigned to the 1st Brigade, 1st Infantry Division. He joined the Army in May 1989 and began serving with the division in October 2007.

To date, 151 Fort Riley service members have died while serving in Iraq and Afghanistan.

Transition team training is a 60-day training cycle at Fort Riley to prepare small teams of soldiers, airmen and sailors to advise, teach, mentor and coach their Iraqi or Afghan counterparts.