Until you fire the first shot you can claim almost anything. Once you start shooting you wind up with the consequences usually. But I can't imagine NK would start a war since the likelihood of winning is zero. Bluster however plays well in NK politics.
The US doesn't bother declaring war anymore. Too much accountability required across the board to meddle with that sort of bureaucracy.
Mutually assured destruction via tweet/policy statement?
It's a brave new world we live in :/
Since Bush declared war on half the world 15 years ago, does it mean they are in mutual agreement now?
If Trump's rhetoric were directed by Russia at the United States... Well, I'd be booking a stay-cation to Australia.