Russia has pulled off a few neat switches since it gained independence from the Soviet Union...
Russia gained independence from the USSR in 1991, like most* of the other ex-Soviet republics. When the USSR (led by Gorbachev) finally imploded after an attempted coup to remove Gorbachev failed, its constituent republics - Russia (led by Yeltsin), Ukraine (Kravchuk) and Belarus (Shuskevich) in the West, Kazakhstan and the other Stans in the South and East - all agreed to go their own way. The USSR became the Commonwealth of Independent States (CIS). Gorby resigned, handing the nuclear codes to Yeltsin on the way out. This peaceful process is what Putin has described as "the greatest geopolitical catastrophe of the 20th century". Yeltsin went on to survive another attempted coup in 1993, Kravchuk lost an election to Kuchma, and Shuskevich to Lukashenko.
Second, Russia worked to seize the mantle of the Soviet Union and to ensure it remained the only nuclear power of this Commonwealth of independent states, a role others were mostly happy to see it take on in view of Russia's size and the constraints of keeping a nuclear deterrent safe: UN Security Council seat, the bulk of the armed forces, etc. Guarantees about territorial integrity were duly given to Ukraine in 1994, not only by Russia but also by the US and the UK. Putin set about consolidating this when he came to power in 2000.
Third, Russia has worked to get this equation Russia = Soviet Union accepted by the other constituent republics of the USSR (at least those with a majority Slavic language, Ukraine and Belarus, and those in the Caucasus). So after the wars in Chechnya, we've had war with Georgia, the seizure of Crimea, the occupation of the Donbass. The "independent republics" around Russia should have no doubt who's in charge: Russia is no longer first among equals, it is the overlord. In parallel, Russia has re-inserted itself into other theaters like the Middle East and Africa and continues to pull some strings in Central Asia.
Putin seems to be mostly bothered about political contagion from Ukraine, Poland and the Baltics. The new prosperity in Poland and the Baltics is troubling, and the ethnic, historical and cultural links with Ukraine are so tight that he doesn't want Ukraine to follow a similar path. He also needs an outside threat/enemy to distract attention from what's going on at home. So he must cut off Ukraine from any kind of rapprochement with the EU, not to mention NATO. Neutralizing countries like Poland, the Baltics, Hungary and Romania all help that.
So what we see now is Russia trying to get the former Comecon/Warsaw Pact countries, the ones that all voted with their feet as soon as they got half a chance in the late 80s and joined NATO in the late 90s, to accept the Russia = USSR equation, too. In effect, Russia is trying to turn the clock back to 1980, before the rot set in, when Russia/USSR had SS20s pointed at Germany and W. Europe and protested vociferously when NATO planned to introduce Pershing missiles in response. He wants the complete neutralization of the Eastern part of the European Union, also including Finland and Sweden to turn the Baltic into a Russian lake, and naturally the withdrawal of all US military components. But he certainly doesn't want to discuss this with the European neighbours: he will talk only with the US. This has all sorts of advantages: it insures some sort of symmetry that he sees as geographically advantageous (Russia is in Europe, the US isn't), it uses the window of opportunity created in the US by internal turmoil (post-Jan 6, post BLM, etc.) and its preoccupations with China, and it divides to conquer.
What on earth are the European nations going to do about this fine piece of revisionism?
*the Baltic Republics had already left between 1988 and 1990
