War on Iran has changed many things, not least of which is the tenor of nuclear debate in two of America’s closest Asian allies: countries that have long defined themselves by the weapons they do not possess.

For decades, the question of whether South Korea and Japan might one day build their own nuclear arsenal was treated as fringe speculation – the preserve of hawks and provocateurs. No longer.

The director general of the International Atomic Energy Agency (IAEA) has sounded the alarm. Veteran Korea watchers speak of a “rationalisation” of nuclear weapons discourse. And a majority of South Koreans tell pollsters they want the bomb.

The debate, long simmering, has come to a roiling boil.

Yet analysts who watch the region closely urge caution before declaring the non-proliferation order in East Asia on the verge of collapse. The obstacles to change – be they economic, diplomatic or structural – are still formidable, even if the psychological ones are eroding fast.

‘Friendly proliferation’?

In an interview published on Monday, IAEA chief Rafael Grossi outlined his “worst fear”: a new global nuclear arms race.