Ukraine wanted to join NATO, and if it joins, NATO will put her military equipments in Ukraine, that's d cause of the problem, Russia warned Ukraine not to join because Russia shares border with Ukraine,

If NATO forces use Ukraine as a base, that means NATO forces would be at Russians backyard with all their weapons pointing at Russia and that is what PUTIN is fighting against.

In d 60s, Russia (defunct USSR) wanted to have her military base in Cuba which is at America's backyard, US kicked against it and invaded Cuba, that's what led to the Bay of pigs invasion, and now d same US wants to have her military base at Russia's backyard under the pretext of NATO.

The best form of defense is attack, which world power would allow the enemy have her military base at her backyard? Who does that??

Also US that destroyed other independent countries like Libya and co have no moral justification on this case.

How will it end?

In addendum, NATO is created for countries bordering the North Atlantic, funny enough Ukraine is not one of those countries which makes it suspicious why NATO would want to have her military base in Ukraine if not for ulterior motives.

When the US made business difficult for some countries around Asia, the Japanese lashed back by clearing pearl harbor and the US in their show of force nuked Hiroshima and Nagasaki.

Now we have the Cryptocurrency/Tesla versus the Oil business war in play. This may be the gate opener for the next war around the world and shall be supported by different country according to how they may profit.