Intelligence sources estimate North Korea has material for sixty nuclear warhead. After multiple test detonations of a yield of ten kilotons or fewer, in 2017 North Korea apparently detonated a hydrogen bomb with a 140-ton yield. However, it’s not clear how much progress has been made miniaturizing the warheads to fit inside a missile.

Although ballistic missiles could deal extensive damage to U.S., Japanese and South Korean military bases, their ability to threaten civilian population centers is ultimately far more important. South Korea and the United States can clearly defeat the North Korean military in a conflict, but the prospect of missiles raining on Seoul, Tokyo and Los Angeles, potentially armed with nuclear or chemical warheads, makes any such conflict unacceptably costly by any sane calculation. While South Korea, the United States and Japan have all deployed air defenses designed to shoot down such missiles, it would only take one nuclear missile landing in a metropolis to kill tens of thousands or worse.

While the North Korea once nearly conquered the South in just a few weeks, today it’s that its military has no hope of defeating its much wealthier and more populous southern neighbor—let alone do so while fighting off U.S. forces. Instead, Pyongyang has built up its capabilities to make a renewed conflict as unacceptably costly to the citizens of its adversaries as possible. This is both to serve as a deterrent from attack, but also as a bargaining chip to boost the impoverished nation’s international clout and leverage economic assistance vital to sustaining its economy, thus keeping the Kim family safely in power.

Sébastien Roblin holds a Master’s Degree in Conflict Resolution from Georgetown University and served as a university instructor for the Peace Corps in China. He has also worked in education, editing, and refugee resettlement in France and the United States. He currently writes on security and military history for War Is Boring.