What is the relationship between Ukraine and Russia? What does it mean to write on the news recently? Who can tell this story in a simple and popular way?

Ukraine and Russia are neighboring countries. They used to be allies of the Soviet Union. Later, after the Soviet Union split, they became independent. What happened recently was that the Ukrainian president fled, which triggered national unrest. When the domestic opposition seized power by snobbery, Russia took the opportunity to launch a veritable aggression in the name of protecting its compatriots. Dear, hope to adopt, thank you!