They might be, but tracing back the news sources, I see a
trouble-maker: [1]
https://en.wikipedia.org/wiki/Andrei_Soldatov
who may be hyperbolizing security tests.
It's not unreasonable for Russia to consider the scenario "Can
we survive?" autonomously. In fact, I rather hope the USA is
doing the same.
Does it mean they want to sever from the world? Or are they
preparing for scenarios?
I tend to believe they're preparing for possible scenarios and
making preparation on the "just in case".
Still, it's good that it's being reported and people are
watching "just in case" this scenario (are they planning
actively to cut off?) is the right one.
References
Visible links
1.
https://en.wikipedia.org/wiki/Andrei_Soldatov