This article is a repackaging of a Vice article:

https://motherboard.vice.com/read/this-theory-about-a-russia...

The Vice article is low on actual maps and photos.

Someone posted to HN a link to a similar article with a lot more visual data

http://www.hisutton.com/Yantar.html https://news.ycombinator.com/item?id=12696753

It's strange that the experts think this is so difficult when there's been so much reporting on this capability in the past.

I mean, I think it's extraordinarily difficult, but governments have thrown a ton of money at the problem. :-(