North Korea’s efforts to develop a nuclear-armed intercontinental ballistic missile capable of hitting the US mainland have accelerated during the first year of Donald Trump’s presidency. The country’s leader, Kim Jong-un, has presided over a series of successful missile tests, including North Korea’s first launch of an ICBM on 4 July, a development he promised in a televised new year’s address. Like all tests, the missile came down in the sea but its trajectory was thought to place Alaska in range of a live strike.

A second test of the Hwasong-14 ICBM less than a month later demonstrated an increased range, potentially including New York. The test on 28 August of an intermediate range ballistic missile, which activated public warnings as it passed over Japan, shows Kim also wants to keep rattling his near-neighbours.

There is a growing consensus that former Soviet missile engines acquired on the black market in Ukraine have enabled Kim’s scientists to take the strides seen this year. A definitive demonstration that North Korea has built a warhead vehicle capable of enduring the extreme heat and velocity of atmospheric re-entry will be one of the last major hurdles they need to clear.

Nuclear tests are also getting bigger

Developing a fully functioning ICBM is only part of the challenge North Korea has set itself. It also needs to produce a miniaturised nuclear bomb that can be loaded on to such a missile to complete a credible weapon. An underground test on 3 September, North Korea’s sixth since they began in 2006 under Kim’s predecessor and father, Kim Jong-il, suggested that milestone may also be within reach.

Pictures released by the regime just before the test showed Kim inspecting a device that appeared in scale with the likely dimensions of the Hwasong-14 ICBM. The regime said this was a hydrogen bomb and while there is no way to verify this claim or whether it was the device that was subsequently tested, the size of the explosion on 3 September makes it plausible. It triggered a magnitude-6.3 earthquake and was significantly more powerful than previous North Korean tests, as well as the atomic bombs dropped by the US on Hiroshima and Nagasaki during the second world war.

What about anti-missile defences?

The US has developed several interceptor systems, which are responsible for defending itself and its regional allies from attack by short, medium and long-range missiles. South Korea hosts Patriot interceptor missiles that can protect single locations, as well as the Terminal High-Altitude Area Defence (Thaad) system which is designed to defend a wider area. The Aegis sea-based system provides a highly mobile regional defence and operates from US, South Korean and Japanese warships. Japan is also considering an upgrade of its land-based ballistic missile defence.

Hopes for defending US territory lie with two Ground-Based Midcourse Defense (GMD) sites in Alaska and California from where missiles would launch to take out an incoming ICBM in space. The shorter-range interceptors have a better record in testing than the GMD, with all tests being carried out in a situation that lacks the unpredictability of a hostile attack. Future North Korean missile development is likely to include functionality designed to confuse or evade anti-missile defences. Source.