So apparently Breitbart has updated their article (I can't, and won't, link it), showing the statutes the warrant was issued persuant to: 18 USC 793, 2071, and 1519
18 USC 793 is for violation of the Espionage Act, with 10 year penalties for each document
793 is for willful/grossfly negligent removal of information relating to the national defense
18 USC 2017 and 1519 are for concealing federal records