Commentary: If Pyongyang says it’ll build more nukes, it will

North Korea signalled to the world that it is seriously back into the nuclear bomb-making business with the announcement that its old nuclear plant at Yongbyon is being reactivated.

And today it heightened the sense of risk and uncertainty by blocking hundreds of South Korean workers’ access to the joint industrial complex it shares at Kaesong — which earns Pyongyang £65 million a year in much needed hard currency.

United Nations secretary-general Ban Ki-moon greeted the news about Yongbyon by saying the current crisis had gone too far. “There is no need for North Korea to be on a collision course with the international community. Nuclear threats are not a game.”

It is pretty clear, however, that the regime of the youthful dictator Kim Jong-un is embarked on a very deadly game. And there seems to be a fair amount of method — and guile — behind the way they are playing their hand.

Yongbyon is a game-changer because it offers the possibility of producing fuel for nuclear bombs and warheads via two routes — enriched uranium and plutonium.

It may take the best part of year, but when the leaders in Pyongyang say they intend to build a lot more nukes, they mean it.

So far their paranoia has been fed by the response of America and its allies, Japan and South Korea.

Their military exercises, which go on to the end of the month, have brought a display of American air power, including the forward stationing of an F-117 Nighthawk Stealth Fighter squadron. There seems something a touch eccentric in such a public show of the Stealth planes.

The display of US military hardware harks back to confrontations of yesteryear. Whatever happened to soft power, and quiet diplomacy behind closed doors?

The confrontational approach fuels the Orwellian regime with fear and suspicion. The conundrum of North Korea this time round seems to have stumped Washington, Beijing and Tokyo as well as Seoul.