A letter report issued by the Government Accountability Office with an abstract that begins "In the absence of underground nuclear weapons testing, the National Nuclear Security Administration (NNSA) relies on its supercomputing operations at its three weapons laboratories to simulate the effects of changes to current weapons systems, calculate the confidence of future untested systems, and ensure military requirements are met. GAO was requested to assess the extent to which (1) NNSA has implemented contingency and disaster recovery planning and testing for its classified supercomputing systems, (2) the laboratories are able to share supercomputing capacity for recovery operations, and (3) NNSA tracks the costs for contingency and disaster recovery planning for supercomputing assets. To do this work, GAO examined contingency and disaster recovery planning policies and activities, and analyzed classified supercomputing capabilities at the weapons laboratories, and NNSA budgetary data."