What is a THAAD ballistic missile defence system?

The Pentagon confirmed today that the US military will deploy a THAAD ballistic missile defence system to Guam.

THAAD, which stands for Terminal High-Altitude Air Defence, is a system that shoots down short and medium range missiles.

It is considered one of the last lines of defence against an incoming threat, does not carry an explosive warhead and travels over twice the speed of a bullet.

Watch the video below to find out more about THAAD.