Talking about justifying things is just a way to do moralizing. The way to avoid conflicts is by developing understanding for the interests and concerns of different nations, and treating one another with respect. After the fall of USSR, the west decided that it can ignore Russia's security concerns and keep pushing an aggressive military alliance onto Russian borders. That's what caused the war.

Plenty of western experts have been warning about this for decades on end. This only became controversial to mention after the war started. Here's what Chomsky has to say on the issue recently:

https://truthout.org/articles/us-approach-to-ukraine-and-russia-has-left-the-domain-of-rational-discourse/

https://truthout.org/articles/noam-chomsky-us-military-escalation-against-russia-would-have-no-victors/

50 prominent foreign policy experts (former senators, military officers, diplomats, etc.) sent an open letter to Clinton outlining their opposition to NATO expansion back in 1997:

George Kennan, arguably America's greatest ever foreign policy strategist, the architect of the U.S. cold war strategy warned that NATO expansion was a "tragic mistake" that ought to ultimately provoke a "bad reaction from Russia" back in 1998.

Jack F. Matlock Jr., US Ambassador to the Soviet Union from 1987-1991, warning in 1997 that NATO expansion was "the most profound strategic blunder, [encouraging] a chain of events that could produce the most serious security threat [...] since the Soviet Union collapsed"

Even Gorbachev warned about this. All these experts were marginalized, silenced, and ignored. Yet, now people are trying to rewrite history and pretend that Russia attacked Ukraine out of the blue and completely unprovoked.

You don't have to justify all invasions to justify some invasions?