The US Navy's warfare systems command just paid millions to stay on Windows XP

That scares the poop out of me. Our DoD systems are actually on an obsolete operating system that is maintaining "SIPRnet.."

SIPRnet is defined as: "The Secret Internet Protocol Router Network (SIPRNet) is "a system of interconnected computer networks used by the U.S. Department of Defense and the U.S. Department of State to transmit classified information (up to and including information classified SECRET) by packet switching over the TCP/IP protocols in a 'completely secure' environment". It also provides services such as hypertext document access and electronic mail. As such, SIPRNet is the DoD's classified version of the civilian Internet. ..."

https://en.wikipedia.org/wiki/SIPRNet