The Justice Department is preparing to seek an indictment against former Cuban President Raúl Castro, three people familiar with the matter told The Associated Press on Friday, amid heightened tensions as President Donald Trump threatens possible military action against Cuba . One of the sources said the potential charges are linked to Castro’s alleged role in the 1996 downing of four aircraft operated by the Miami-based exile group Brothers to the Rescue, when he was Cuba’s defense minister. All three individuals spoke on condition of anonymity because they were not authorized to discuss an ongoing investigation. The possible indictment, which would require grand jury approval, was reported earlier by CBS. As Trump seeks to wind down the war in Iran, speculation has been growing that he may soon turn his attention back to Cuba (AP Photo/Julia Demaree Nikhinson) The AP reported in March that the U.S.…