By ABC national affairs correspondent Greg Jennett
Tough talk travels fast when fury is fired back and forth between Washington and Pyongyang - and speed now matters more than ever.
Rocket science may well be left to do what diplomacy has been incapable of - pulling two reckless personalities back from the brink of war.
By North Korea's boastful reckoning, its Hwasong-12 missiles will take just 1065 seconds to complete their 3356km flight over Japan before splashing down in waters off the coast of Guam.
If correct, and if the US allows the missiles to launch in the first place, that leaves 17 minutes for tracking stations on land and sea - including the Pine Gap facility near Alice Springs - to calculate, target and try to destroy the missiles.
The US and its north Asian allies monitor and measure all North Korean missile tests but have traditionally not attempted to fire them down for two key reasons.
Each flight reveals valuable data about the Kim regime's progress in ballistic development and shooting one down would only add to what analysts in the pre-Trump era used to call the "risk of miscalculation".
It is a quaint notion these days because every presidential statement seems carefully calculated to risk calamity.
Coupled with Kim Jong-un's outrageous capacity for hyperbole, is it any wonder that the world is watching?
With Donald Trump's every utterance, the chances of the next test near Guam being left militarily unanswered are dangerously diminished.
As commander-in-chief, Mr Trump can rely on a menu of Pentagon plans to either prevent or retaliate against any missile test near US territory in the Pacific - there are many of them and some are drilled regularly in Guam.
The outpost is home to vast US military assets at Andersen Air Base and in Apra Harbour and an installation of the THAAD missile shield system is reportedly a fixture there.
As a last line of defence, military analysts believe the system stands a better chance of targeting an incoming missile later in its flight than in earlier phases.
But US plans do not rely on THAAD alone - many more attempts at intercepts can be made from Japan or ships beneath the flight path before the missile splashes down at a threatened distance of 30-40km off the coast of Guam.
It is a measure of the desperate stakes involved that Australian Prime Minister Malcolm Turnbull has uniquely offered a pre-emptive declaration of military support under the ANZUS alliance - without knowing what form any conflict may take or what risks are involved.