WASHINGTON • A re-engineered American interceptor rocket collided with a mock intercontinental ballistic missile (ICBM) in the skies over the Pacific Ocean, the Pentagon said, in the first successful test of whether it could shoot down a warhead from North Korea racing towards the continental United States at speeds approaching true battle conditions.
The US military fired the ICBM-type missile from the Kwajalein Atoll in the Marshall Islands towards the waters just south of Alaska. It then fired a missile to intercept it from Vandenberg Air Force Base in California.
Experts compare the job to hitting a bullet with another bullet, and note that the complexity is magnified by the huge distances involved.
At a time when tensions with North Korea are running high, a successful test is vital for the Defence Department's beleaguered missile defence programme. It enables the Pentagon to argue that it is making strides in protecting the US from a North Korean nuclear warhead.
But even advocates of the programme stopped short of arguing that it could now provide a defensive shield. With Tuesday's test, only five of the last 10 tests have been declared fully or partly successful in the 13 years since the system became operational.
The results of the test were being scrutinised, not only because a failure would have been a major setback, but also because a redesigned interceptor was put up against a dummy warhead that was speeding towards the US at a velocity close to that of a real incoming missile.
The test "demonstrates that we have a capable, credible deterrent against a very real threat", said Vice-Admiral James Syring, the director of the Pentagon's Missile Defence Agency, calling the test a "critical milestone for this programme".
But Defence Department officials provided no details, saying only that initial indications showed the test had met its primary objective by hitting the target, and that the missile agency would evaluate other data to determine how the system performed overall.
The test was the first of a new "kill vehicle" that uses thrusters to aim directly at an incoming warhead. This is intended to solve a persistent technical problem blamed for many past misses.
So far, North Korea has not tested a missile that could reach the US, but experts expect that moment in the next five years or so.
The continental US is around 9,000km from North Korea. ICBMs have a minimum range of about 5,500km, but some are designed to travel 10,000km or farther.
To truly threaten the US, North Korea would have to show it has a missile that can reach the West Coast or farther inland, and it would have to shrink a nuclear warhead to fit atop an intercontinental missile and survive the stresses of re-entering the atmosphere.
Pyongyang has also been working hard to overwhelm the defence systems that the Pentagon has placed in California, where the anti-missile system was tested, and in Alaska. For instance, North Korea regularly practises firing salvos of missiles because the US system is designed to intercept only one or two incoming warheads at a time.
Analyses of recent North Korean flight tests and missiles paraded through the streets of Pyongyang suggest that it may also be seeking to develop manoeuvrable warheads. Such a tactic, if successfully developed, would help warheads dodge anti-missile interceptors.
For that reason, former US president Barack Obama had ordered in 2014 that the traditional missile defences be supplemented by a covert programme intended to sabotage launches before they happen. That programme includes electronic warfare attacks, but it is unclear how successful it has been.
Experts say a combination of sabotage and interception of airborne missiles represents the best chance of protecting the US.
The North Koreans recently test-fired a series of missiles based on a technology that would give the US little warning of an attack. Their new missiles use solid fuels and can be launched in minutes. That makes the already daunting job of intercepting them far harder, given that the US anti-missile system works best with early alerts from satellites that a launch is imminent.
While the US missile defence test on Tuesday was not "timed specifically to the current tensions", the North "remains a cause for concern", said Pentagon spokesman Jeff Davis.
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