Despite a six-year effort to build trusted computer chips for military systems, the Pentagon now manufactures in secure facilities run by American companies only about 2 percent of the more than $3.5 billion of integrated circuits bought annually for use in military gear. That shortfall is viewed with concern by current and former United States military and intelligence agency executives who argue that the menace of so-called Trojan horses hidden in equipment circuitry is among the most severe threats...