Well I think in an ideal world "liberating" would not involve mass murder of the "liberated" population. I am aware that this is a historical weak spot.

Even still - I don't see a problem with countries rescuing other countries from despotism, in principle. I eagerly include my own country in this - if a Putin-like figure arose and I was not permitted to speak out or face death, it would comfort me to know that help was coming. The terror of an oppressive regime is its inescapability.