I'm sure they'd be upset, but the USSR was the first country to overfly other nations with a man made object in space. I doubt they'd do anything other than yell about it? It's not like they could effectively sanction the US.

I am not an expert in these matters but, if I understand correctly, they can tell velocity and direction to see that it's not going to hit then. I'm not sure that it enters their airspace, however.

Are there any treaties or international laws regarding this? Again, Google is not being helpful.