The Air Force is beginning to explore its options for replacing the unarmed aircraft used to fly nuclear supervision missions under the Open Skies Treaty, expecting that the OC-135B will be in service for 80 years. Boeing built the original aircraft in 1962, which was modified to serve the Open Skies mission after the treaty was signed in 1992. The treaty allows signatory countries to monitor one another's domestic military operations on short notice, then share that information with the...