An intercontinental ballistic missile (ICBM) travels at six and a half kilometres per second. Or, in other words, twenty times the speed of sound.

The North Korean missile that crossed over Hokkaido in Japan before landing in the Pacific wasn’t an ICBM. It was a mid-range missile travelling about half as fast.

Given the missile’s trajectory and flight path, it’s fair to see its launch as an open challenge by North Korea to Japan – but not as a challenge to US bases in Guam, or at least, not yet.

Why the North Korea nuclear crisis will return with a vengeance

The United States’ so-called theatre missile defence system in Asia – which incorporates anti-ballistic missile systems in Japan, South Korea and Guam – is capable of neutralising the dangers posed by North Korea’s mid- and intermediate-range missiles, which can strike locations up to 1,000kms away.

However, even America’s homeland security systems cannot guarantee being able to block ICBMs, which have a range of 3,000km.

The Pentagon has tested the ability of America’s homeland defence systems in neutralising incoming ICBMs on 19 occasions. On 18 of those, it judged its systems to have passed the test.

Given there’s a chink in America’s armour, dialogue remains essential.

But the likelihood of dialogue is receding. Why?

Trump’s nuclear standoff with North Korea: why this is no Cuban Missile Crisis

Much of the world sees Pyongyang as weak, and is seeking to make it even weaker with various sanctions.

Pyongyang realises this, and won’t come to the table unless it feels some semblance of strength. This is the North Korean conundrum.

Without a full-fledged ICBM capability, Kim Jong-un knows he cannot strike terror into the hearts of US decision makers.

And North Korea is still lacking such a capability, despite its two ICBM tests in July. The latest research by scholars at the Middlebury Institute of International Studies in Monterey, California, suggests that two tests are too few to indicate a mature capacity in this regard.

Indeed, even when considered in addition to the sixteen other missile tests Pyongyang has carried out this year, there’s little to suggest any recent breakthrough by North Korea in enhancing its offensive capabilities.

Opinion: North Korea is addicted to missiles – if intervention fails, it’s war

It may be grappling with the science of atmospheric re-entry, but Pyongyang’s military scientists still have little real world evidence to go on.

This is why Kim has already launched more missile tests this year than the 17 conducted throughout his father Kim Jong-il’s entire tenure.

He knows that without increasing his missile capability his hand is too weak to engage in negotiations.

He is in this position partly because of North Korea’s penchant for constant bluster – it has long issued more threats than its military is capable of carrying out. On a daily basis, there is an endless stream of rhetoric against the US/South Korea/Japan and occasionally even China, too.

Kim needs his missiles to back this bluster up and hence he keeps testing them, as he knows he does not yet have the whole spectrum of capabilities – the kind of arsenal needed to act as a complete deterrent to any US aggression.

North Korea would need another fifty successful ICBM tests – in which missiles re-entered the earth’s atmosphere – before it could credibly claim an ability to breach America’s theatre missile defence system in Asia, let alone its homeland defences.

Furthermore, as North Korea is yet to carry out its sixth nuclear test (though this could occur at almost any moment) Kim knows that, missiles aside, there is another missing component to his weapons programme.

With more sanctions creeping in, he will find it only harder to acquire new parts for this programme, and this will feed the paradox facing other nations in their handling of North Korea.

More sanctions will make it even more important for North Korea to indeginise its defence capabilities – making it more important than ever in Pyongyang’s eyes to keep testing its missiles.