The Department of Defense on Thursday placed the University of Phoenix system on probation, barring the for-profit school giant from recruiting on military bases and preventing troops from using federal money for classes.

The Defense Department provided few details on the move, but the university system US:APOL has been subjected to scrutiny by the department and Congress for months. In June, Sen. Dick Durbin (D., Ill.) sent a letter to Defense Secretary Ash Carter requesting an investigation into, among other things, the school’s recruitment efforts on bases.