Appease him with shiny objects to his face, while surreptitiously eroding his power base and when possible, outright sabotage his operations under the guise of his underlings' incompetence. Exactly what we've done with NK for decades.
Well, that strategy of containment certainly isn't directly aggravating, but I will point out that North Korea's sociopolitical climate aren't improving, and their arsenal is growing ever more powerful. I am uncertain, however, whether better could be expected.
But I find it useful perhaps to consider a case example:
You are the parent of an adorable but highly ego-centric 3 year-old boy. Let's name him Donny. Donny is sitting at the dinner table with you, chowing down on a gigantic bowl of spaghetti-o's. The adults are discussing something and he feels left out. So he raises a big spoonful of spaghetti-o's as if to sling it directly at your face. Luckily you notice and respond with a gentle "no-no Donny". But it doesn't work. Full-on toddler meltdown happens. Tears, snot-bubbles, the works. What do you do?
A. Point your finger at him and laugh at how small he is and can't even go through with throwing his spoonful of spaghetti-o's at you.
B. Tell him to "shut up already", smack him across the face, and keep on with your conversation.
C. Tell him "No Donny. Don't cry. You shouldn't feel upset. It's just spaghetti-o's."
D. Put him in immediate time-out for 10 minutes.
E. Grab a cookie and give it to him so he calms down and forgets about the spaghetti-o's, and while he's eating the cookie substitute the spaghetti-o's for a grilled-cheese sandwich so he can't make a giant mess.
F. Tell him "Donny, when you raised your spoon that made daddy feel really upset at you, and it's not good to make daddy upset, food is something that is yummy that we are supposed to eat and poop out, and throwing food is bad because it will make a mess and then you'll make me clean it up, and then we'll have to put you in a time-out after, and you don't want that do you?"
G. Tell him "I see you're upset. You can't throw your food. If you start to do so again, you will have a time-out until you're calm enough to join the family." When Donny raises his spoon again, take it from him but don't put it in time out because he didn't sling it at you and seems content to get a rise out of you.
H. Tell him "I see you're upset. You can't throw your food. If you start to do so again, you will have a time-out until you're calm enough to join the family." When Donny raises his spoon again, put him in time-out for 10 minutes even though he's calmed down to teach him a lesson not to do it again.
I. Tell him "I see you're upset. You can't throw your food. If you start to do so again, you will have a time-out until you're calm enough to join the family." When Donny raises his spoon again, put him in time-out and explain to him for 2 minutes why throwing his food is bad.
J. Tell him "I see you're upset. You can't throw your food. If you start to do so again, you will have a time-out until you're calm enough to join the family." When Donny raises his spoon again, put him in time-out until he is calm enough to join the family. After dinner is over, explain to him in toddler-appropriate language that he can't throw food and what you will do if he tries again in the future.
Personally, I think we should not confront his powerlessness nor should we artificially inflate his sense of power. We should communicate a reasonable limit and a reasonable action, and if the limit is crossed respond with that reasonable action which does not escalate the conflict. And when he is no longer at peak narcissistic vulnerability we should be as explicit as possible in negotiating clear boundaries and consequences and attempt to ally toward a goal of gradual de-escalation while being impressed at how strong of a leader he is to be humble enough to negotiate for peace.