The Naval Academy is digging sextants out of their storage spaces and asking the Merchant Marine Academy (which never stopped teaching celestial navigation) and training its students in celestial navigation so that the ships will still be able to find their way after their adversaries infect the GPS system with malware.
The class of 2017 will graduate with certification in celestial navigation.
Old school navigation pales in comparison to today's high-tech systems. It's both painfully difficult and far less precise. But it can get you where you need to go within about 1.5 miles (2.4 kilometers). That could be a matter of life and death in a scenario where modern technology has been compromised.
US Navy Revives Ancient Navigation as Cyber Threats Grow
(Image: Pilot Officer J H Smythe of Sierra Leone, a newly-qualified navigator, being instructed in the use of the sextant by an instructor at No. 11 Operational Training Unit, Westcott in Buckinghamshire, 1 August 1943, public domain)