U.S. Investigation Into Leak of Classified Pentagon Documents Focuses on Insiders

The U.S. government is treating the apparent disclosure of classified material surrounding the war in Ukraine as an insider’s leak, people familiar with the matter say, and is working to identify and apprehend a key suspect in a massive intelligence breach that has exposed the challenges of safeguarding sensitive U.S. information and tested ties with some of America’s closest allies.

Investigators are pursuing a range of leads in the fast-moving inquiry, one of the people said, including some that surfaced as the Washington Post reported late Wednesday that the classified information was posted to a private social-media group by a man claiming to be employed on a U.S. military base.

The bulk of the more than 60 documents, if genuine, appear to originate from the Central Intelligence Agency’s Operations Center and the Pentagon’s Joint Chiefs of Staff. Such documents are typically briefed to senior-level decision makers at the Pentagon in an environment protected from electronic surveillance and secured against leaks.