The Defense Department's best efforts to prevent the cost of new weapon systems from skyrocketing "have not had a material effect" and the "status quo is both unacceptable and unsustainable," according to David Walker, the U.S. comptroller general. In a letter accompanying a new report examining a substantial slice of the Pentagon's weapon system acquisition portfolio, Walker, the head of the Government Accountability Office, finds that "new programs continue to move through development" without mature technologies, stable designs and controlled...