Massachusetts Air National Guard member Jack Teixeira, who was sentenced last year to 15 years in prison for leaking highly classified military documents, is scheduled to begin his court-martial on additional charges Monday. Teixeira pleaded guilty last year to six counts of willful retention and transmission of national defense information under the Espionage Act, following his arrest in the most consequential national security breach in years. In his court-martial, Teixeira faces charges of disobeying orders and obstructing justice. At a hearing last year, military prosecutors said a court-martial is appropriate given that obeying orders is the absolute core of the military. But Teixeira's lawyers argued that further action would amount to prosecuting him twice for the same offense. The court-martial panel is convening at Hanscom Air Force Base in Massachusetts. The leaks exposed to the world unvarnished secret assessments of Russia's war in Ukraine, including information about .