There is no threat to border nations. Georgia, for example, attacked their provinces, and Russia used the fact that in USSR these provinces were not part of Georgia.
So no threat to border nations. As long as Russia doesn't decide their nation isn't valid.
Ukraine started to attack Russian-oriented population
No they didn't.
and Russia used the fact that in USSR (and before that) Crimea was part of Russia.
No it wasn't. Crimea was part of Ukraine in the USSR (though it was part of Russia before that).
Who else? Finland. A former province of Russia. Member of EU and important trade partner of Russia. They had war in 1939, when USSR demanded exchange of territories - they wanted to have more land between the border and St.Petersburn (then Leningrad). Finland refused, and this ended up with terrible war. Russians got what they wanted, and paid a price that allowed them to withstand Hitler's attack. Later, Spanish friends of Hitler blockaded St. Petersburg causing hundreds of thousands of people to die of starvation, but they would have a better chance if Russians wouldn't have that war before.
Finland still remembers that war and some unstable Finnish boneheads still hate Russia for it. However, there are no tensions between two countries and I can't imagine them to have a military conflict.
So the USSR wanted some of Finland and Finland refused so the USSR attacked them.
And somehow you think Finland is the one to blame?
These two didn't exist before the USSR. In fact, Latvia was part of Russia for around 300 years. They never had nobility (dukes, princes, whatever) and even their language was first formalized in 19th century by Latvians who studied in St. Petersburg. Without Latvians, communism wouldn't win in Russia after the Great War, as Latvians were the main power of Lenin. So, that was a genuine part of Russian Empire and this worries Latvians. They have a territory dispute with Russia over the territory that was never part of Latvia but was promised by Lenin. If Latvia wouldn't be part of EU and Nato, they, IMHO, could be in some danger, especially taking into account that large part of population (more than half in capital) are ethnic Russians.
So another pair of border nations Russia doesn't really recognize and would like to invade but currently can't do so safely.
They had so good relations with Russia that eventually became part of it. And yes, I am talking about Tartars.
The Tartars who got expelled from Crimea by the USSR, came back when it was part of Ukraine, and are overwhelmingly against this recent annexation.
Well, speaking about China - they have the main quality of an ally for Russia - they don't betray their allies. Neither does Russia.
Except of course Ukraine.
Who else? Canada. Is hostile towards Russia because of Arctics. Both countries want control over it. Everything else are merely excuses.
Canada has bigger territorial disputes over the Arctic with Denmark and the US. No hostility there. And Canada isn't hostile to Russia, we just strongly disapprove of fascism and wars of expansion.
Georgia. Home of Joseph Stalin. Ex ally and friend of Russia. Neither Russians or Georgians are hostile towards each other, but Russians deeply disapprove the political decisions of Georgia. Current leaders of Georgia are way more adequate than their predecessor, but they can't undo the damage (i.e. return two republics to Georgia), as Russia recognized the independence of both South Osetia and Abkhazia.
Russia assisted the independence of South Osetia and Abkhazia, along with Transnistria in Moldova.
You spent a lot of time pointing out Russia wasn't a threat to nations it had good relations with and no claims to. Well of course they aren't a current threat to those nations. But the moment Russia's mood changes, or they feel they're owned some of the land, you've demonstrated that Russia will simply try to take it. By your own story Russia is a massive threat to bordering nations.