There's a lot of documented cold war era espionage stuff about tapping undersea cables. Eg https://nationalinterest.org/blog/buzz/intelligence-coup-how-one-us-n

There's a lot of documented cold war era espionage stuff about tapping undersea cables. Eg https://nationalinterest.org/blog/buzz/intelligence-coup-how-one-us-nuclear-submarine-tapped-russian-undersea-cables-159086 https://nationalinterest.org/blog/buzz/intelligence-coup-how...