The U.S. Air Force announced on Monday that it had penalized 15 people after an investigation into classified information leaks by Jack Teixeira, a former member of the Massachusetts Air National Guard’s 102nd Intelligence Wing. The Air Force sent an August report to Congress on Monday saying that while 21-year-old Teixeira—who posted photos of hundreds of classified documents on Discord— committed the alleged crime by himself, members of his unit “had information about as many as four separate instances of his questionable activity.” “After interviewing higher levels of the supervisory chain, it appears knowledge of these security incidents was not fully disclosed above the squadron level,” the Air Force inspector general’s office said in its report. “Three individuals in the unit who understood their duty to report specific information regarding A1C Teixeira’s intelligence-seeking and insider threat indicators to security officials, intentionally failed to do so.” In a statement, the Air Force said that some of the 15 disciplined individuals, ranging in rank from staff sergeant to colonel, were removed from their positions. On Monday, Air Force Secretary Frank Kendall said, “Every Airman and Guardian is entrusted with the solemn duty to safeguard our nation’s classified defense information.”