Defense Secretary Chuck Hagel is ordering top-to-bottom changes in America's nuclear forces, vowing to invest billions of dollars to fix the management of the world's deadliest weapons, according to two senior defense officials. Hagel made the decision after concluding that problems are rooted in a lack of investment, inattention by high-level leaders and sagging morale, the Associated Press reports. Hagel ordered two lengthy reviews of the nuclear force after a series of stories by the AP revealed numerous problems in management, morale, security and safety, leading to several firings, demotions and other disciplinary actions against a range of Air Force personnel, from generals to airmen.