President-select George W. Bush yesterday selected Donald H. Rumsfeld, a veteran Washington insider and champion of missile defenses, to be secretary of defense. Picking Rumsfeld, a former Navy fighter pilot and Illinois congressmember, brings to the Pentagon’s top job a man with a military experience and stature on Capitol Hill to press Bush’s priorities to modernize the armed forces and build a missile shield against what they perceive as emerging threats. Rumsfeld, more than any other, has driven the debate over whether to build a national defense system. In 1998, the former Republican congressman, former ambassador to NATO and former secretary of defense oversaw a commission that concluded that “rogue” nations could threaten the United States with ballistic missiles sooner than analysts had predicted. The commission’s report and a North Korean missile test a month later led the Clinton administration to propose its own limited version of a national missile defense. Republican Senator Jon Kyl, an ardent advocate of a missile defense system, said the Rumsfeld report was the main reason the debate was gradually turned around and the administration turned around.