Russia's no more reliant on undersea cables than the US is, although there's something to be said for air-gapping Russia at the interchange level. That won't completely cut them off (look at a map) but it'll make it less convenient for them to surreptitiously operate on US networks.
Written by Bob Koure
Retired software architect, statistical analyst, hotel mgr, bike racer, distance swimmer. Photographer. Amateur historian. Avid reader. Home cook. Never-FBer