WASHINGTON—A federal grand jury added new charges on Wednesday against three men charged with conspiracy to kidnap Michigan Gov. Gretchen Whitmer, saying they planned to use weapons of mass destruction to destroy a bridge, the Justice Department said. Adam Fox, 40, of Wyoming, Michigan; Barry Croft Jr., 45, of Bear, Delaware; and Daniel Joseph Harris, 23, of Lake Orion, Michigan, were charged with knowingly conspiring to use weapons of mass destruction against persons or property, the department said, in addition to a kidnapping conspiracy charge in October. The superseding indictment on Wednesday alleges that the three planned to destroy a nearby bridge, which would have harmed and hindered Whitmer’s security detail and any responding law enforcement officers, a Justice Department statement said. The new indictment also alleged that Croft and Harris possessed a “destructive device” that was not registered as required by U.S. federal law. It said Harris also possessed …