I guess the UN could pass a resolution to authorize an invasion (though they can't really enforce anything). It's why the US presented their case against Iraq t

I guess the UN could pass a resolution to authorize an invasion (though they can't really enforce anything). It's why the US presented their case against Iraq to the UN 20 years ago. Though in this particular case, the demands Putin made before the invasion, that NATO should promise never to allow Ukraine in, and should abandon eastern Europe entirely, sounded a lot to me like Putin was basically demanding permission to invade those countries. Because while NATO can't give permission to invade, it can most certainly enforce a denial of that permission by defending the target of the invasion. And that's what Putin was asking from NATO: a promise not to defend Ukraine or any other country in eastern Europe.