The recent claim by Kim Jong Un that North Korea plans to develop the world’s most powerful nuclear force may well have been more bravado than credible threat. But that doesn’t mean it can be ignored.

The best guess is that North Korea now has sufficient fissile material to build 45 to 55 nuclear weapons, three decades after beginning its program. The warheads would mostly have yields of around 10 to 20 kilotons, similar to the 15 kiloton bomb that destroyed Hiroshima in 1945.

But North Korea has the capacity to make devices ten times bigger. Its missile delivery systems are also advancing in leaps and bounds. The technological advance is matched in rhetoric and increasingly reckless acts, including test-firing missiles over Japan in violation of all international norms, provoking terror and risking accidental war.

The question now is how best to bring the pariah nation into the orbit of arms control negotiations and international dialogue. However remote the chances of that, the alternative risks a regional nuclear arms race.