"Special military operation" in Ukraine is carried out in order to prevent the Third World War. Dmitry Medvedev, Deputy Chairman of the Security Council of the Russian Federation, stated this in an interview with the French TV channel LCI.
“We must do everything so that the third world war does not happen, and the policy of our country is aimed precisely at this,” Medvedev said (quoted by Interfax). He explained that World War III could start if Ukraine joined NATO and then launched a military operation against Russian territory.
Medvedev also said that the "special operation" "is proceeding according to the most sparing, moderate option" and that the Russian military is conducting military operations only against the Armed Forces of Ukraine.
If the situation had been different, then, as you understand, this military campaign could have ended much faster. But there would be completely different consequences for Ukraine. Its infrastructure would be completely destroyed, decision-making centers, authorities and so on would be destroyed. We didn't go for that option.
Medvedev also stressed that now there are no grounds for Russia to use nuclear weapons. He recalled that this can only happen in response to someone else's nuclear strike or "other actions that threaten the existence of the state itself."