Updated May 31, 2017 09:04:23

The United States military has successfully staged its first-ever missile defence test involving a simulated attack by an intercontinental ballistic missile (ICBM), as concerns mount over North Korea's advancing missile and nuclear program.

"This system is vitally important to the defence of our homeland, and this test demonstrates that we have a capable, credible deterrent against a very real threat," Vice Admiral Jim Syring, the director of the Missile Defence Agency, said in a statement.

The Missile Defence Agency said the test involved launching a simulated ICBM from a test site on Kwajalein Atoll in the Marshall Islands toward the US.

US forces — using data from satellites and radar — then fired a Ground-based Midcourse Defence (GMD) interceptor from the Vandenberg Air Force Base in California to strike it down.

Photo: People watch as the ground element missile defence system flies from California. (Reuters: Lucy Nicholson)

"The intercept of a complex, threat-representative ICBM target is an incredible accomplishment," the Missile Defence statement added.

"A critical milestone for this program."

Ahead of the launch, a successful test was by no means guaranteed, and the Pentagon sought to manage expectations, noting that the US had multiple ways to try to shoot down a missile from North Korea.

"This is one element of a broader missile defence strategy that we can use to employ against potential threats," Pentagon spokesman Captain Jeff Davis said.

'Like hitting a bullet with a bullet': experts

Photo: North Korea seeks to build nuclear-tipped missiles that can reach the US mainland. (Reuters/KCNA (file photo))

North Korea has dramatically ramped up the pace of its missile tests over the past year, with a goal of developing an ICBM that can strike the US mainland.

The continental US is about 9,000 kilometres from North Korea. ICBMs have a minimum range of about 5,500 kilometres, but some are designed to travel 10,000 kilometres or further.

Experts said a successful intercept would be much like hitting a bullet with a bullet, and cautioned that the ICBM would be traveling faster than any missile in previous GMD tests.

There's been a lot of focus on the country's nuclear ambitions, but Pyongyang's military is already vast and powerful.

Ahead of the launch, Riki Ellison, the founder of the Missile Defence Advocacy Alliance, described the test as "vital".

"We are replicating our ability to defend the United States of America from North Korea," Mr Ellison said.

However, critics have long questioned how much protection a ground-based interceptor could provide.

A 2016 assessment released by the Pentagon in January said US ground-based interceptors meant to knock out any incoming ICBM still had low reliability, giving the system itself a limited capability of shielding the US.

"There are already significant questions about the capability of this system and how much protection it actually provides," the Arms Control Association's Kingston Reif said.

Had Wednesday's test failed, Mr Reif warned that it could have deepened concern about a weapons program that — according to one estimate — has cost the US more than $US40 billion ($54 billion) so far.

Photo: Californians watch the interceptor missile launch from an underground silo at Vandenberg Air Force Base. (AP: Len Wood)

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Topics: defence-and-national-security, world-politics, donald-trump, united-states, korea-democratic-people-s-republic-of

First posted May 31, 2017 07:41:23