The US has started the process to deploy an advanced missile defence system, the Terminal High Altitude Area Defence (Thaad) in South Korea to better counter growing threats by North Korea, Seoul’s defence ministry announced on Tuesday.

Parts of the anti-missile system arrived on Monday at Osan Air Base in Pyeongtaek, 70 km south of Seoul, Yonhap News Agency reported.

Thaad is composed of six mobile launchers, 48 interceptors, X-band radar and the fire and control unit.

Also on Monday, North Korea fired off four ballistic missiles in protest against the ongoing military drills between Seoul and Washington.