Luck is a combat veteran of both the Vietnam War and the Gulf War and has held a variety of command and staff positions throughout his army career, to include: Chief of Staff, 8th Infantry Division, U.S. Army, Europe; Director, Force Programs, Office of the Deputy Chief of Staff for Operations and Plans, HQ Department of the Army; Assistant Division Commander, 101st Airborne Division; Commanding General, 2nd Infantry Division, Korea; Commanding General, Joint Special Operations Command (1989–1990); Commanding General, U.S. Army Special Operations Command; and Commanding General, XVIII Airborne Corps during Operation Desert Shield and Operation Desert Storm (1990–1993). His last military assignment before retiring from active duty was as Commander-in-Chief, United Nations Command (Korea)/Combined Forces Command/United States Forces Korea.