Nothing. Anything they build can never be used against anyone else in the six-way talks. The retribution would be earth shattering, and North Korea has to know that. Chinese and Russian protection, which saved them during the Korean War, would evaporate.
Let them build rockets that barely work and nuclear bombs that fizzle. Let them stave their country and rob their citizens of basic necessities like food, water and power. Ever see a satellite image of North Korea at night? There are practically no lights. It’s like there’s no electricity in the whole country. How can we possibly take a state like this seriously?
The United States has made a monumental mistake in catering to North Korea for so long. Because they are the most advanced of our enemies we have taken them a little too seriously, seen them as a military threat in a way they never deserved. The more time and energy we expend dealing with this backward Communist nation the more we validate their little crusade for global power. God help us if one of their missiles actually works someday. Their demands will increase tenfold, and we will have given them just cause to expect such compensation.
