Gates' address to 400 U.S. Air Force personnel followed the firing last week of Air Force Secretary Michael Wynne and Chief of Staff Gen. Michael Moseley after a series of embarrassing and potentially catastrophic mishaps over the past year.
Speaking to reporters, Gates said fixing the nuclear stewardship issue will be the most important task for replacement nominees Pentagon official Michael Donley and Gen. Norton Schwartz, The Denver Post reported Tuesday.
"Accountability must reach all the way up the chain of command," Gates said in a speech given at the Peterson Air Force Base auditorium near Colorado Springs.
Gates' speech reflects the growing concerns about U.S. credibility and U.S. nuclear facilities in Europe, say observers.
"The view of a lot of my counterparts in other countries, until these incidents, was that the United States had the best nuclear security in the world. Now it's not clear we can make that statement," Charles Ferguson, science and technology fellow at the Council on Foreign Relations think tank, told the Post.
Notable deaths of 2014 [PHOTOS]