What is the THAAD missile system, where is the US program deployed and how does it work?

THE THAAD missile system could be the only line of defence against trigger-happy tyrant Kim Jong-un as he threatens to nuke his enemies in Asia and the US.

Here's the lowdown on the state-of-the art kit which has been deployed in South Korea to guard against the threat from the North Korean dictator.

What is the THAAD missile system and how does it work?

The Terminal High Altitude Area Defence (THAAD) system is designed to intercept and destroy short and medium-range ballistic missiles during their "terminal" phase of flight when they are falling towards the target.

The $1billion system was developed by the Pentagon following the failure of Patriot air-defence missiles to shoot down Saddam Hussain's Scud rockets in the first Gulf war.

THAAD missiles are 20ft long, weigh nearly a ton and fly at up to 6,300mph, more than eight times the speed of sound, up to an altitude of around 93 miles.

They do not carry an explosive charge because it could detonate the warhead of the target missile - which could contain a nuclear device.

Instead they rely on a "hit-to-kill" approach, using infrared sensors to track the incoming missile and ramming it head-on to destroy it.

Admiral Harry Harris, who heads the US Pacific Command, said THAAD will “be able to better defend South Korea against the growing North Korean threat”.

China “firmly opposes” the system’s arrival in the region, which it views as a threat to its own security.

This is because it could possibly shoot down its own nuclear missiles.

A typical THAAD battery includes at least six launcher vehicles, each capable of firing eight missiles.

Why did the US test THAAD recently?

Incredible footage showed the US military shooting down a missile similar to the ones launched by North Korea.

US forces tested their Terminal High Altitude Area Defence (THAAD) system in Alaska at an incoming target over the Pacific Ocean.

The medium-range ballistic missile was detected, tracked and intercepted on July 31, military bosses have revealed.

The test was a show of force two days after Kim Jong-un launched his latest missile – and then bragged it could hit anywhere in America.

Kim has also threatened to "reduce South Korea to ashes" after Seoul's joint missile defence drills with the US military.

It follows North Korea's underground test of what it claims is a 120 kiloton hydrogen bomb. and the threat of further tests of the regime's long-range missiles that could theoretically hit as far away as Chicago.

Where is the US program deployed?

THAAD is deployed in South Korea in an unusual location.

American troops set the system up on a former golf course in the southern county of Seongju in May 2017.

The Pentagon is weighing up whether to install missile interceptors on Hawaii, which could be one of the first parts of the United States in range of an improved North Korean missile.

The United States already has missile interceptors in California and Alaska that can supposedly stop any ballistic threat coming over the Pacific, but experts say these systems need strengthening.

THAAD has also been deployed in Turkey and the United Arab Emirates.