The US military has moved parts of THAAD, the Terminal High Altitude Area Defence System to South Korea on 26th April 2017.
The earlier-than-expected steps to deploy the Terminal High Altitude Area Defence (THAAD) system was also denounced by North Korea even as South Korea's presidential election are on May 9, 2017.
South Korea's Defence Ministry indicated elements of THAAD were moved to the deployment site, on what had been a golf course, about 250 km south of the capital, Seoul.
The battery was expected to be operational by the end of the year, it said.
The United States and South Korea agreed in 2016 to deploy the THAAD to counter the threat of missile launches by North Korea. They say it is solely aimed at defending against North Korea.
But China says the system's advanced radar can penetrate deep into its territory and undermine its security, while it will do little to deter the North, and is adamant in its opposition.
China is North Korea's sole major ally and is seen as crucial to US-led efforts to rein in North Korea.
The United States began moving the first elements of the system to South Korea in March after the North tested four ballistic missiles.
South Korea has accused China of discriminating against some South Korean companies operating in China because of the deployment.
The United States and North Korea have been stepping up warnings to each other in recent weeks over North Korea's development of nuclear weapons and missiles in defiance of UN resolutions.
North Korea says it needs the weapons to defend itself and has vowed to strike the United States and its Asian allies at the first sign of any attack on it.
The United States is sending the USS Carl Vinson carrier strike group to waters off the Korean peninsula, where it will join the USS Michigan, a nuclear submarine that docked in South Korea.
South Korea's navy has said it will hold drills with the U.S. strike group.
Kim Jong-un had supervised the country's “largest-ever” live-fire drill to mark 25th April''s 85th founding anniversary of its military, with more than 300 large-calibre, self-propelled artillery pieces on its east coast.
