MAD still applies, disincentivizing a direct war between the US and Russia. US nuclear policy is unspecified, Russian policy explicitly calls for the use of nuclear weapons if the survival of the Russian state is on the line. Direct war with the US could very easily lead to the Russian state fearing for its future.

> Direct war with the US could very easily lead to the Russian state fearing for its future.

Yes, that's another dimension in this complex problem.

You’d be staking out the ground first as ‘your fight’ - so in general maybe.

In this case for instance, if NATO had moved in before Russia into Ukraine however, that would be really, really bad.

A big factor behind this war already is Russian insecurity about NATO strength and being frozen out of traditionally Russian territory.

It would be a bit like Russia occupying some of the Aleutians all the sudden. Not likely to go well. Sudden double flashes not well.

Thanks for your answer which is insightful. As you explain there is asymmetry in the case of countries that are close to a border of one of the actors (either US or Russia).

So can we expect other similar moves from Russia into countries that are not part of NATO and which have no common frontiers with US?

They have been for awhile. Georgia, for instance.

They’ve been threatening countries like Finland, Sweden, etc. every time they consider it too.

When it was non-western aligned Soviet breakaway republics, it was easier to ignore.

The invasion of Ukraine was too obvious and ham handed. Moscow has doubled down on the threats to those on the fence since then, enough to push folks back over to the other side.

Which likely just pushes Russia more solidly into doubling down/existential threat mode.

Here is some timely news on the topic.

[https://news.yahoo.com/finland-and-sweden-moving-toward-poss...]

That depends on whether you like to see your metal objects glow in the dark.