All that is just repetition of the excuses for Russia's aggression.
Until the Security Council makes a ruling, Ukraine has the right of self defense, period. It is the UNSC that resolves such disputes, not one of belligerents.
Your own attempts at legalism have no bearing. It is not illegal for any nation to join any alliance they choose. That's what sovereignty means.
Russia violated Ukraine's sovereignty in 2014 by annexing Crimea and setting up statelets the Donbas, and is now attempting to conquer the entire country by force.
Since the aggressor is a member of the UNSC, it takes the Security Council out of the role it's supposed to be serving. That leaves only force to settle the matter.
Any P5 nation that chooses that path must be prepared to suffer the consequences.
Wrong.
Since Russia in on the Security Council, there can never be a ruling against Russia.
But we all also know the Ukraine is the criminal perpetrator.
It is illegal for the Ukraine to try to put NATO nukes on Russia's border.
Russia is well within its defensive rights to prevent the Ukraine from joining NATO.
Trying to join NATO violated the 1992 treaties, so then the Ukraine forfeits its independence, and reverts to a state of the USSR.
The sovereignty of the Ukraine is not based on inherent rights of natives, but instead was granted by treaty, so then is automatically revoked by treaty violations.
Instead then the rights of native become the justification for legal authority, and then the ethic Russia areas have the right to their own independence.
What you also conveniently forgot to mention is that the Crimea, Donetsk, etc., are NOT ethnically, traditionally, legally, or historically part of the Ukraine.
The Ukraine illegally stole them when Khrushchev the Ukrainian, just gave them to the Ukraine in 1955, even though they legally, traditionally, and historically were always part of Russia.
The US and the Ukraine are fighting to preserve the illegal dictates of a supreme dictator.