These are your words: "wonder how the US would react to some random country dropping a bomb".
Yes, and it's a shame that you're not understanding the point of the sentence.
A "random bombing" would be a target picked (or fired) completely at random. It might hit a lake, a seagull on a cliff, a hospital full of people, The President, etc.
A "random country" is an emphasis on it could be from any country, but it does not specify their target was random.
I was responding to Jaskalas's comment specifically on the point of "do we need to?" [ask permission before bombing someone else's country], and my implied counterpoint is that generally speaking, it would be more civilised to do that. If say Germany dropped a bomb to kill a target in America, it would cause a hell of a diplomatic stink, but there's probably a hundred countries at the very least in which it would be "OK" to a Western country to drop a bomb in, and not OK by the West if it was say Russia or China that did it.
Not that I'm defending Russia or China's foreign strategies for a minute, just pointing out a Western hypocrisy, such as the one that allows Israel to commit genocide, bomb whichever neighbour they like, etc.