A 2006 book by Frederick Kagan examining the evolution of U.S. military doctrine and the need for adaptive strategies in modern warfare. The scholarly analysis outlines three major phases of transformation in U.S. military policy, structure, and doctrine following the Vietnam War: the shift to an all-volunteer force and new weapons systems in the 1970s; the development of stealth technology and precision-guided munitions in the 1980s; and the emergence of information-age strategies and 'transformation' concepts in the 1990s after the Cold War.