"I joke with people and say it’s the Air Force’s oldest IT system. But it’s the age that provides that security,” Rossi said in an October interview. “You can’t hack something that doesn’t have an IP address. It’s a very unique system — it is old and it is very good.”

In 2016, the Government Accountability Office wrote that SACCS runs on an IBM Series/1 computer dating from the 1970s and that the Defense Department planned “to update its data storage solutions, port expansion processors, portable terminals and desktop terminals by the end of fiscal year 2017,” but it’s unclear whether those upgrades have occurred.

https://www.c4isrnet.com/air/2019/10/17/the-us-nuclear-forces-dr-strangelove-era-messaging-system-finally-got-rid-of-its-floppy-disks/