A retired four-star Marine Corps general who served as the nation’s second-ranking military officer is a target of a Justice Department investigation into a leak of information about a covert U.S.-Israeli cyberattack on Iran’s nuclear program, a senior Obama administration official said. Retired Gen. James E. “Hoss” Cartwright served as deputy chairman of the Joint Chiefs of Staff and was part of President Obama’s inner circle on a range of critical national security issues before he retired in 2011. The administration official said that Cartwright is suspected of revealing information about a highly classified effort to use a computer virus...