Well they both are across the large ocean and it's difficult to invade US from their location (especially for NK which probably doesn't even have ships). US is surrounded by weak, peaceful countries and separated by oceans from not-so-peaceful ones. It could cut the military spending completely and still be safe.
You're not accounting for the fact that it is in America's best interests to have allies, most of whom are across those same oceans. And vice versa.
They won’t have any choice soon enough - all that wishy washy they are not our enemy bullshit goes out the window with the first missile/shell/drone flying over.
Why would Russia/NK attack their wannabe ally?
Something something the frog and the scorpion
If you remember Putin is a spy by training, and a damn good one at that, you must consider spies really don’t want to change things when they are advantageous to them. Right now he knows very well what levers to pull to make things happen the way he wants. He won’t change that.