Late Stage Anglo-American Empire

I can honestly agree with this idea but I feel you'll need to do a lot more than just kill cops and soldiers... The citizenry of the USA is heavily indoctrinated and worse still are extremely aggressive. If they're not openly hostile they'll be covertly hostile and it will take time and effort from both within and without to break that spirit. Remember, the Nazi's got their ideas from the USA and it's ancestors in Europe... It took 2 world wars and an unimaginable amount of dead to break the Europeans lust for war and even now it slowly is coming back, imagine what it will take to break the USA, a nation that has never had to fight for its life really ever.

Socialism will have to be forced on them at gunpoint

I mean, that's basically what a revolution is, at least the initial part. You want to get and keep the confidence of the people too (and part of that is making sure their needs are met, which is part persuasion and part plain actually caring about what happens to people). But you can't expect to have control over that pre-revolution and hope people will go along with an overthrow of an existing system. Revolution isn't a dinner party, a picnic, or a campaign promise. There's a relevant quote about how it's the forceful imposition of one group on another, or words to that effect, I forget the exact quote or I'd post it.

Could just cut off trade. USA is so reliant on imports it would just collapse.