The text mentions spy satelites as the main factor that came later, as well as cruise missiles etc. But still, radio triangulation was a known technic and subm

The text mentions spy satelites as the main factor that came later, as well as cruise missiles etc. But still, radio triangulation was a known technic and submarines did exist and should have been expected to be build by the sovjets, so I am still wondering a bit, why the dedection issue was not mentioned.