Explainer: What made North Korea test giant new ICBM?

In firing an almost cartoonishly massive intercontinental ballistic missile into space, North Korean leader Kim Jong Un has turned back the clock to the fire and fury days of 2017 as he revives nuclear brinkmanship aimed at pressuring the US to accept his country as a nuclear power and remove crippling sanctions.

Thursday's launch of the Hwasong-17 was North Korea's most provocative weapons test since US President Joe Biden took office and underscores Kim's determination to continue building his military while diplomacy remains frozen.

This experimental launch is worrying because the weapon is being developed to be armed with nuclear bombs and to threaten Washington, DC, New York and much of the rest of the world.

The North, however, may need more tests including of nuclear bombs in coming months as Kim tries to both perfect his technology and get a response from the Biden administration, which is distracted by Russia's invasion of Ukraine and an intensifying rivalry with China.

Here's a closer look at Kim's new missile and what he may be up to next:

DOES SIZE MATTER?

At around 25 metres (82 feet) long, the Hwasong-17 is by some estimates the world's largest road-mobile ballistic missile system.

North Korea revealed the missile during a military parade in October 2020, and Thursday's launch from an airport near the capital Pyongyang was its first full-range test.

Kim could be seen in images released by his state media relishing the test's success as he walks past the missile wearing sunglasses and a black leather motorcycle jacket.

He leads military officials along the airport's runway in a scene reminiscent of a Hollywood action movie, at one point whipping his shades off to stare at the camera.

North Korea last flew an ICBM in November 2017 when it tested the Hwasong-15. That was during a run of nuclear and missile tests that led to an exchange of insults and threats between Kim and then-US President Donald Trump, who said the North's threats against the US would be met with fire and fury like the world has never seen.

While Hwasong-15 demonstrated the potential to reach targets in the American homeland, the latest test displayed a missile that could possibly travel even farther.

The Hwasong-17, which was fired at a high angle to avoid the territorial waters of neighbours, reached a maximum altitude of 6,248 kilometres (3,880 miles) and travelled 1,090 kilometres (680 miles) during a 67-minute flight before landing in waters between North Korea and Japan, according to North Korea's state media.

The flight details were similar to assessments by the South Korean and Japanese militaries and suggested that the missile could reach 15,000 kilometres (9,320 miles) when fired on a normal trajectory. That would effectively place the entire US mainland within striking distance.

Extending its ICBM range is crucial for North Korea as it tries to build a more credible nuclear threat to target the US, said Lee Choon Geun, an honorary research fellow at South Korea's Science and Technology Policy Institute.

To strike the US mainland, North Korea's previous ICBMs would have had to pass Alaska, where the US deploys a larger number of missile interception systems.

Hwasong-17's extra range could theoretically allow the North to avoid Alaska by travelling westward so that it reaches the US mainland by way of the Atlantic Ocean, Lee said.

WILL THE WARHEAD SURVIVE?

North Korea's development of a larger ICBM could be a reflection of a desire to eventually arm it with multiple nuclear warheads to improve its chances of defeating missile defences.

It, however, may take years and major technological advancements to perfect such designs.

It also remains unclear after Thursday's launch whether the North has solved the problem of ensuring that its ICBM warheads can withstand the harsh conditions of atmospheric reentry.

While extensively reporting other details of the launch, the North's state media made no mention of whether any warhead survived.

Japan's Chief Cabinet Secretary Hirokazu Matsuno said that Japan may try to retrieve missile debris to analyse the North's technology.

Lee said North Korea could conduct more Hwasong-17 tests, including launches over Japan so North Korean scientists could see how it operates at a more normal trajectory.

The North in 2017 conducted two launches over Japan of an intermediate range missile potentially capable of reaching Guam, a major US military hub in the Pacific.

IS A NUKE TEST COMING?

North Korea is showing signs that it may be restoring tunnels at its nuclear testing ground that it detonated in 2018, as Kim tried to leverage his nukes for badly needed economic benefits from the US.

Kim held his first summit with Trump weeks later. The diplomacy derailed after their second meeting in February 2019, when the Americans rejected the North's demands for major sanctions relief in exchange for a limited surrender of its nuclear capabilities.

The site in Punggye-ri in the country's northeast was used for its sixth and most recent nuclear test in 2017.

After declaring the site's closure, Kim invited foreign journalists to observe the destruction of tunnels in May 2018, but did not invite outside experts to certify what had been destroyed.

Some South Korean analysts said the North may feel the need to resume nuclear tests in coming months to get the attention of the Biden administration, which has offered open-ended talks but showed no willingness to concede on sanctions.

The missiles the North tested this year included a purported hypersonic weapon and short-range solid-fuel missiles targeting South Korea.

Analysts said the North may use another nuclear test to claim it had acquired the ability to produce a nuclear warhead small enough to fit on those missiles.