OREANDA-NEWS/ Each THAAD system is comprised of five major components: interceptors, launchers, a radar, a fire control unit and support equipment, according to Lockheed Martin, the security and aerospace company that serves as the prime contractor for the equipment.
Here's how it works, Lockheed Martin says.
The radar first detects an incoming missile. Those manning the system identify the threat. Then, a launcher mounted to a truck fires a projectile, which Lockheed Martin calls an "interceptor," at the ballistic missile in the hopes of destroying it using kinetic energy -- basically just its sheer speed.
Why South Korea is using it

Because it has no warheads on its missiles, instead destroying other projectiles by colliding with them, THAAD is "potentially safer, especially for dealing with nuclear missiles," said Yvonne Chiu, an expert on military policy and diplomacy at Hong Kong University.
"If you hit a nuclear ballistic missile with a missile with no warhead, it would hopefully not cause a nuclear explosion."
South Korea announced Wednesday that it would deploy the system in the country's south in order to protect it from a a potential attack.
Unlike North Korea's mostly untested ballistic missiles program, THAAD has been in use for several years by the U.S. military to protect units in places such as Guam and Hawaii from potential attack.
"North Korea continues to develop their nuclear weapons and ballistic missile programs, and it is the responsibility of our Alliance to maintain a strong defense against those threats," Gen. Curtis M. Scaparrotti, Combined Forces Command, U.S. Forces Korea commander said last month.
"THAAD can add an important capability in a layered and effective missile defense."
Why is it controversial?

While the U.S. maintains that any deployment of THAAD in South Korea would be solely to protect its forces there and their South Korean allies, some see it as further militarization of the peninsula and an escalation of the American presence there.
China especially, tends to view any increase in U.S. military presence in Asia as an attempt to contain it and reduce the effectiveness of its weapons.
Speaking at an event hosted by the Center for International and Strategic Studies think tank in February, Chinese Foreign Minister Wang Yi said the deployment of the anti-missile system could jeopardize "China's legitimate national security interests."
Anti-war activists hold placards during a rally against THAAD in 2016.