The left is basically parroting the exact same language 
  the right did for all its foreign interventions. 

GWB's invasion of Iraq was America breaking international law. I was against that.

The Russian invasion of Ukraine is Russia breaking international law. I am against that.

I am for whatever strategy (military aid? diplomacy? alliances?) most effectively addresses the Ukraine invasion and limits future illegal invasions. Nobody can know yet which strategy would be best, but it's not hypocrisy to be open to military aid, etc. I want to live in a world where leaders obey the rules.

And I’m not sure I understand the jump from “i oppose X” to “the US must get involved with X”.

Noam Chomsky is critical of Russia’s invasion, just like you.

But doing “something” is an entirely separate decision. People seem to be operating with the default of “if there is a problem, the US has an obligation to fix it”

It’s that mentality that has gotten us into so much trouble over the past 60-70 years.

My opinion is the default is “we do nothing”, and anything more needs justification and a careful analysis to ensure we don’t make things worse (which has been the outcome of almost every intervention since WW2).

One bad thing about GWB's wars is that the global community failed to prevent or meaningfully punish them. That precedent increases world-wide recklessness and paranoia.

I worry that if the outcome of the Ukraine is not a spectacular failure for Russia, the world will continue backsliding (I bet there are Chinese generals rallying already to take Taiwan)

What faith remains in the rule of law internationally is important to preserve. Eg: if the Hague had managed to imprison Cheney et al, would Russia today dare to invade neighbors?

My worries there are why I am open to escalation, though, like you, I fear it could escalate up to some kind of extinction event :(