Going after the monsters that murdered thousands of Americans was entirely justified.
Russia's problem is that all their reasons for invading Ukraine, they made up. The very people Russia claims to have been 'saving', are the ones that they are disproportionately killing.
How about NATO attacking Yugoslavia unprovoked? Was that a nasty business?
NATO attacking Libya, unprovoked, was that a nasty business?
The USA attacking Afghanistan unprovoked, was that a nasty business?