I don't think we have any standing to declare that "God isn't mad at America" or that "He's not mad at anyone" either. What we know of God's nature is from the Bible, and from it we Americans have reason to fear God's justice. Buchanan's article is worth reading, for it reveals as much about America as it does about Russia. When I contemplate the miraculous blessings that founded, established and sustained America for over two centuries, and then examine what we've more recently done with those blessings, I tremble at the thought of a just, righteous and omnipotent God. We are in great danger.
God would be unrighteous to judge America for sins already judged on the body of his son. Jesus said, "It is finished." Contrary to the traditions of man in popular Christian culture, God isn't mad at anyone. He wants to being America back to himself, and may yet do so. God himself brought America into existence for a specific purpose and will not let her go until that purpose is fulfilled. I'm not sure America has fulfilled her purpose yet.
America has a role to play against the likes of tyrants and bullies like Putin.