It announced a capability to reach mainland US with its missiles, a feat that will limit America's options in retaliating against any attack on South Korea or Japan if Kim Jong-un's military machine figures out how to fit them with nuclear warheads.

Anyone hoping the US will navigate what is a treacherous and complicated path forward - beset by variables that the best military and policy minds may not anticipate - may be dismayed after a scroll through US president Donald Trump's Twitter feed.

A look back over the last six months will show the world cannot approach this stand-off as it did during the Obama or Bush 2 eras. For a start, North Korea has amassed considerable weapons by developing its ICBMs, and holds a lot more bargaining power.

Just as important, the rapid ascent of North Korea's missile technology and its repeated provocations have coincided with a decline in US global leadership and status, hastened by Mr Trump himself. Historians may cast this as the first major crisis to take place in a brave new multipolar world, where the impulsive New York property magnate presides over a superpower far less in control of the future.

It may be too much to hope for, but it would benefit all sides in this conflict if the US and South Korea accepted this now. The US risks disaster by treating the Korean peninsula as the stage to enact any delusion it wields the dominance it once had, or to exorcise doubts it may not be the lone superpower it once was.

Given this, the US and South Korea's response to Mr Kim's missile test, particularly its joint missile exercise, should be viewed with scepticism by onlookers. It risks further escalating the conflict with little pay-off in the way of leverage that may bring the North Koreans back from further aggression. But hopes of harmony returning to the Korean peninsula in the short seem unlikely. The North Korean regime knows its very survival depends on maintaining some sort of uncomfortable stand-off with the US. They are well aware that the consequences of a US strike would be potentially disastrous for their own population, but have a strong ace card in the knowledge that an all-out war that could involve mass casualties in South Korea, Japan and now possibly further afield is an unthinkable risk unacceptable to most sane-minded western decision makers.

Mr Trump seems to understand the limits of US power in the stand-off, if his tweets about China's role in reigning North Korea back show anything. His Secretary of State Rex Tillerson has called for a global solution. It's how Mr Trump, the US military and the State Department react to those restrictions that will largely define how this conflict ends - that, and the frightening unpredictability of the North Korean regime.

European players, Australia and other middle powers should not underestimate their role in steering the conflict to an end that doesn't involve what the US Defense Secretary James Mattis said "would be probably the worst kind of fighting in most people's lifetimes." The waning of US influence is also a time for these countries to step up, and this week's G20 summit is an ideal forum. A good starting point would be to de-escalate the conflict, and hold back from any more muscle-flexing.