The Republic of Korea announced on Thursday that it had completed the installation of the remaining four launchers of the Terminal High Altitude Area Defense anti-missile system, and the battery will be operational as soon as the United States finishes its internal procedures. A THAAD unit comprises six truck-mounted launchers, 48 interceptors (eight each launcher), and AN/TPY-2 radar and other ancillary equipment.

The deployment of THAAD, to begin with, is contrary to ROK President Moon Jae-in's earlier statement that the antimissile system should not be deployed in a hurry. In fact, when US troops in the ROK started deploying THAAD on April 27, a couple of weeks before he took office, Moon "strongly objected" to the move.

Moon changed his decision mainly for two reasons: the Democratic People's Republic of Korea's sixth nuclear test on Sunday, which has made the ROK feel even more insecure; and the importance Moon attaches to Seoul's ties with Washington and the deployment of THAAD is a good way of expressing that.