First, this article has nothing to do with Trump. Second, based on the letter it looks like payroll information on DOD employees was leaked. Third, for DISA controlled networks there are three main types. Niprnet, Siprnet,, and Jwics. Nipr is for non classfied info. It is kept as private as possible. Sipr is for Classfied information typically at the secret level. More care and precautions are taken for securing sipr than what you would use for nipr communications. Lastly we have JWICS. This is the network used for Top Secret communications (like POTUS comms) etc. This network uses extensive use of specialized encryptors and the likes. So if a sipr breach occurs it has nothing to do with JWICS communications.