In November 1949, Guthrie returned to the United States and was assigned to the 39th Field Artillery Battalion, 3rd Infantry Division, Fort Benning, Georgia.

During this period, he participated in operations against guerrillas in the Wonsan area, the evacuation from Hŭngnam, the reoccupation of Seoul and the spring Chinese offensive and United Nations counteroffensive.

He was then assigned to the Staff, Commander-in-Chief, Pacific, Camp H. M. Smith, Hawaii, serving as Deputy Chief, War Games Branch, and group operations officer, from August 1961 to February 1964.

In July 1965, he returned to the Continental United States and was assigned to the Requirements and Development Division, J-5 Directorate, Organization of the Joint Chiefs of Staff, Washington, D.C.

In retirement, Guthrie was director of the Association of the United States Army's Landpower Education Program, a position he filled until December 1986.

He also served as a trustee of Princeton University from 1981 to 1985, was on the board of directors of the Army and Air Force Mutual Aid Association and the board of advisors of the National Contract Management Association, and as a member of the National Research Council's Space Technology Assessment Panel and its Committee on Artificial Intelligence and Army Robotics.