Never has Donald Trump looked so wrong and so dangerous as he did in the final debate against Hillary Clinton, huffing and puffing and sweaty-upper-lip sniffing over nuclear weapons.

He overstated Russia’s nuclear might. He disowned his own words. He lost his barely contained temper when Clinton said she finds the prospect of Trump’s finger on the nuclear button “terrifying.”

"Look, she's been proven to be a liar on so many ways,” Trump pouted. “This is just another lie.”

It was no lie. Clinton simply had the temerity to quote Trump himself to show how little he knows or cares about the fragile set of post-World War II agreements that have contained nuclear proliferation. She said Trump would let non-nuclear countries go nuclear. "There's no quote,” he said. “You won't find a quote from me."

Yes, we will.

A few months ago, Trump said, “more countries, such as Japan, South Korea or even Saudi Arabia, may need to develop their own nuclear weapons.”

At a rally in April, Trump told supporters that if conflict between Japan and nuclear-armed North Korea were to break out, “it would be a terrible thing but if they do, they do”.

“Good luck,” he added. “Enjoy yourself, folks.”

That’s scary talk.

So scary that Clinton is likely to win the presidency despite a nagging inauthenticity and dishonesty that moderator Chris Wallace sought to expose. He asked about her email scandal and the many conflicts of interests that entangled her state department and the Clinton Foundation. She dodged his question.