Why Do We Need to Protect Ourself From Foreign Invaders?

A russian could look at the situation and say, the only way that my country can be protected from foreign invaders is for us to control a significant amount of territory so that we can have defense through depth. You could argue that russia's actions are morally defensible by providing for the defence of russia. This is where you go and you say, lookn his has aggressed upon us. Nato is expandingr at our flank, and the united states and its allies and all the native allies are messing around, and they're meddling in our elections and all kinds of things. And that's basically what people have pointed to to say that this was inevitable.