"The radar system for THAAD will be delivered within this month to undergo an operational test," the official told Yonhap News Agency asking not to be named.

The remaining elements will be gradually delivered in the coming months and transferred from the US air base to the southeastern rural county of Seongju, about 300 km south of Seoul, the site for the battery, he said.

The deployment could be completed within one or two months and it can be operational as early as April, another official said Tuesday.

The personnel needed to deploy the THAAD elements in Seongju and give the system a test run are expected to come from THAAD units in Guam and Fort Bliss, Texas, he said.

A THAAD battery consists of six truck-mounted launchers, 48 interceptors (eight per launcher), a fire control and communications unit, and an AN/TPY-2 radar.

THAAD is designed to intercept short and mid-range missiles, such as Scud and Rodong, which have a range of up to 3,000 kilometers at altitudes of 40-150 kilometers.

Seoul and Washington have said the system is purely defensive and poses no threat to other countries in the region. But China has opposed it, arguing the system's powerful radars could spy on its flights and missile launches.

On Tuesday, China's foreign ministry said Beijing will take "necessary measures" to protect itself against the deployment and warned that the US and South Korea should have to bear the consequences.

The response comes a day after Pyongyang test-fired four ballistic missiles that flew about 1,000 kilometers before splashing into the East Sea in an apparent protest against the ongoing joint military drills between Seoul and Washington.

Seoul analyzed the rockets as Scud-ER missiles, "improved versions" of the short-range Scud missile, which usually has a range of 500-700 km. (Yonhap)