North Korea has been very successful in denying the United States and others information about its nuclear weapon program. The result is a high degree of uncertainty about the size and character of the North Korean nuclear weapon threat, how it might be used, and what impact it might have.
A Rand Corporation documented briefing addresses those uncertainties and finds significant uncertainty in how much external help the North Korean nuclear program has received, leading to uncertainty about the number and nature of North Korea’s nuclear weapons.
There is also some evidence that help has included providing fissile material and assistance in designing nuclear weapons, including miniaturization for ballistic missiles.
North Korea uses its nuclear weapons in peacetime for deterrence and to achieve leverage in negotiations, and it would similarly pursue nuclear coercion and deterrence in conflicts. Available information suggests that it would be willing to use nuclear weapons in a conflict to demonstrate its capabilities and resolve.
Like other countries that have developed small nuclear forces, North Korea could threaten adversary cities (mainly in Japan and the Republic of Korea) in an attempt to control escalation, striving for some hope of victory.
If North Korea actually attacked a city such as Seoul with a nuclear weapon, it could result in hundreds of thousands of casualties and serious economic damage.
