The Navy has suspended two admirals in a broadening bribery scandal that already has ensnared three senior naval officials. Involving charges of prostitution and payoffs, the scandal is the U.S. military’s highest-profile case of officer misconduct this year — part of a trend that has caused deep concern among Pentagon officials. The number of substantiated cases of misconduct has increased steadily since 2008, according to statistics by the Defense Department’s inspector general. The Navy is investigating Vice Adm. Ted Branch, director of naval intelligence, and Rear Adm. Bruce Loveless, director of intelligence operations, on accusations of “illegal and improper relations”...