US has reassured Beijing that the deployment of an extensive missile defence system in South Korea is not a threat to China. The Terminal High-Altitude Area Defense system is known as Thaad. This system is designed to protect South Korea and US troops based there.

China fears that the Thaad advanced radar capabilities could threaten Chinese military operations. The BBC reports the first stage of the Thaad deployment came after North Korea launched four ballistic missiles. The UN Security Council condemned the North Korean action.

The Council threatened to take further sanctions against North Korea. Three North Korean missiles came down inside Japan's exclusive economic zone. Japan's Prime Minister Shinzo Abe and US President Donald Trump stated the region had entered a new stage of threat.

More details about the Thaad

The Thaad shoots down short and medium-range ballistic missiles in the final phase of their flight. It uses hit-to-kill technology - where kinetic energy destroys the incoming missile. The Thaad has a range of 200km and an altitude of 150km. 

When the enemy launches a missile, the Thaad radar system detects the attack, then, it launches an interceptor missileThe enemy projectile is destroyed in the final phase of flight. The launcher trucks can hold even eight interceptor missiles.

South Koreans living in places which will host defence batteries are concerned they could become targets. China stated that Thaad goes far beyond what is required for defence. State Department spokesman Mark Toner said the Thaad system is not a threat to China.