Jack Teixeira is expected to plead guilty in the Trove of Secrets leak

A Massachusetts Air National Guardsman accused of posting dozens of classified intelligence reports and other sensitive documents on a social media server is expected to plead guilty Monday in federal court.

Federal prosecutors told a judge Thursday that the defendant, Jack Teixeira, planned to change his plea after initially pleading not guilty. A person familiar with the proceedings also said the airman had agreed to a settlement.

Airman Teixeira is accused of mishandling national defense information and classified documents. Prosecutors say he took the material from computers at an intelligence unit at an Air Force base in Cape Cod and shared it with online friends in an attempt to impress them.

Secrets revealed included information on the supply and delivery of military equipment to Ukraine and a highly sensitive report on Russian and Ukrainian troop movements. Officials said the revelations about the troop movements may have compromised how U.S. intelligence collected the information and from whom.

Pilot Teixeira posted the information online over a period of months.

This is a development story. Check back for updates.

Glenn Thrush reporting contributed.