The U.S. Air Force has proposed in the Fiscal Year 2019 budget to convert three KC-135R aerial refueling tankers into WC-135R nuclear sniffers.
By Ken H / @chippyho [CC BY-SA 2.0], via Wikimedia Commons
“Analysis determined that it was more cost effective to convert KC-135R aircraft into WC-135Rs than to modify existing WC-135W aircraft to be on par with the rest of the C-135 variants ,” said the service.
Two of the existing WC-135s are also becoming more difficult to service.