So back in the 90s Ukraine ended up with the #2 quantity of nukes in the world, this made Russia and US very nervous, so BOTH signed the Minsk Agreement which said BOTH would protect the Territorial Integrity of Ukraine against "all comers" and they gave up the arsenal for verified de-commissioning.
(they dint have the actual sw launch codes, obviously a trivial exercise with 60/70s equipment for most on this forum)
They obviously didn t read history as pretty much everybody in history from Ethiopia(1930s) to Poland(WW2) got left in the cold once shooting starts...until the half-sleep get half-ready.
Lesson re-learned by Iran, North Korea, India, Pakistan, China and others, major Nuke armament development coming.....China is increasing their arsenal by 10x "officially".
Now Russia invades another country in the Year 2022, and threatens all with annihilation if "you help the victim" WOW
Unfortunately for the Russians, the victim in this case is well versed in the end-result of living under a Russian Overlord and will mostly fight to the death instead.
They already saw what happened in Crimea in 2014 when the Russian Army, stripped of all markings (the Little Green Men they were called) brazenly took over the whole place and cleaned house of all potential non-supporters in a classic Commie Purge.
Also, a bunch of other neighbors Having listened to Putin's Multiple speeches on the subject of Re-Building the Soviet Empire/by force if necessary (of course necessary as NO country has ever volunteered to join the Russian Federation) have gone "all in" with the chips to stop the Russians in Ukraine instead of their own country, as Putin has made no secret of his list.
And Bully for the Ukrainians! I thought the whole place would fall in 3-4 days too, and instead the mighty Russian Army has utterly failed with huge losses and proved they are a hollow force with crap equipment and low morale(look up videos of 1960's T-62 tanks now being brought to front from reserves as they seem to be almost out of T-80/72s, also some nice vids of WW2 era rustbucket trucks in use now on front, wow), of course they are not defending their homes and family which is what people fight for...not some BS about empire building, or changing a country from X to Y.
(even the US could not do that in Iraq or Afghanistan-even wasting an incredible 300M$ a day for 20 yrs there/plus 2500 dead and uncounted Afganis)
Cheers