Canada

You could put a Davy Crockett in conspicuously beefy wheeled luggage, it's true. Or a backpack worn by a muscly special forces dude, like in the picture. I feel like people picture a skinny briefcase when you say "suitcase nuke", though.

Access from nation states cooperating with your nation state “can be made easy”. US has made everyone angry, and won’t know who hit them. A single nuclear detonation in US would collapse its government, currency and economy due to already being up against sustainable debt limit.

Who are we thinking of, North Korea? Russia likes the new guy in America, and China likes stability. India and Pakistan have no dog in this fight, and everyone else was a steadfast ally just months ago.

First off, that's the sort of thing that will take more than a lunch to arrange. Second, the level or recklessness here is crazy, and killing thousands of civilians with a first strike would make us the bad guy. Third, debt load won't mean very much if they have the kind of political will that would produce.

I guess I should point out we'd have no trouble making our own nuke if we really needed it, too. There's hundreds of tons of plutonium mixed in the spent fuel we have in storage right now, and we have lots of people who can design the thing.