It happened some half hour before midnight on Saturday, Washington time. The US Geological Survey's Earthquake Hazards Program picked up an explosion with a 6.3 magnitude. The North Korean regime of Kim Jong-un had seemingly succeeded in testing a hydrogen device, bringing the number of nuclear tests to six so far.
President Donald Trump, kept to his usual form. Instead of urging measured calm, he expressed initial awe followed by threat. 'North Korea has conducted a major nuclear test. Their words and actions continue to be very hostile and dangerous to the United States.'
Most problematically, Trump had little patience for Seoul, which would be very much in the line of fire in any opening salvo on the peninsula. 'South Korea is finding, as I have told them,' he tweeted, 'that their talk of appeasement with North Korea will not work, they only understand one thing!'
It did not take long for observers to pick up that Trump's consternation may have been curried by other factors, not least of all his distinctly negative approach to an agreement he claims benefits South Korean companies. The South Korean-US free trade deal is set for a dramatic axing.
It is evident from this stance that neither national security advisor H. R. McMaster or Gary D. Cohn of the National Economic Council have much sway in convincing the president. Even in the shadow of a conflagration, Trump will still seek his variant of the deal.
Defence Secretary James Mattis was tasked with the onerous mission of putting flesh on the bones of the US reaction. 'Any threat to the United States or its territories including Guam, or our allies, will be met with a massive military response, a response both effective and overwhelming.'
Trump, he informed those gathered, had been briefed on 'many military options'. But Mattis must surely know that options, as he has alluded to before, vary on their feasibility. He said, in a mildly reassuring way, that the US was 'not looking to the total annihilation of a country, namely North Korea, but as I said, we have many options to do so'.
In Australia, the reactions have been far from mild. Prime Minister Malcolm Turnbull was less than reassuring, suggesting the un-testable notion that the Korean peninsula was closer to conflict than at any time since the Korean War.
"Julie Bishop suggests cutting oil supplies in an effort 'to bring unprecedented pressure to bear'. Her stress is on