SEOUL, South Korea — South Korea is pushing for deployment on its soil of a US high-altitude air defense system as North Korean missile threats expand.

The move has stoked fears in China, which believes deployment of the Terminal High Altitude Area Defense (THAAD) system could help Washington to expand its military power in the region.

South Korea is prioritizing THAAD deployment with US Forces Korea (USFK) rather than purchasing the weapon system.

"Deployment of the THAAD system needs to be seen in the perspective of national defense and security," Defense Minister Han Min-koo said Jan. 25 during an interview with a local TV station. "There is a limitation to our capabilities, so there is a military need for a thorough review of the THAAD."

His comments came on the heels of South Korean President Park Geun-hye's support for the THAAD deployment.

"The deployment of THAAD will be considered based on our security and national interests and also by taking into account the North's nuclear and missile threats," Park said in a Jan. 13 national address.

Seoul’s increased interest in THAAD came after North Korea conducted its fourth nuclear bomb test on Jan. 6. Previously, Seoul claimed it could defend against North Korean missile threats with its own low-tier missile defense network, dubbed KAMD, including used PAC-2 systems bought from Germany.

"A deployment of THAAD is an inevitable option now for South Korea given the escalating threats of North Korea's missile technology," said Kim Dae-young, a research member of the Korea Defense & Security Forum, a Seoul-based private defense think tank.

× Fear of missing out? Sign up for the Early Bird Brief, the defense industry's most comprehensive news and information, straight to your inbox. Thanks for signing up. By giving us your email, you are opting in to the Early Bird Brief.

Should the North fire nuclear-tipped missiles toward the South, Seoul has few options, as the PAC-2 systems can only shoot down missiles at an altitude of 15 kilometers, Kim said.

"THAAD is designed to intercept missiles at an altitude of 40 to 150 kilometers using a hit-to-kill approach. That means there are double chances to shoot down incoming missiles," he said. "Combining the THAAD with the country's low-tier missile defense network is expected to create a synergy effect in enhancing deterrence against the North."

The cost for deploying the THAAD batteries is a hot button issue. South Korean defense officials said at least two THAAD batteries should be deployed to help thwart the North's missile attacks.

Operating a single THAAD unit is estimated to cost about $1.6 billion. One unit consists of six truck-mounted launchers, 49 interceptors, a fire control and communications unit, and an AN/TPY-2 radar.

South Korea pays about 50 percent of costs for the presence of USFK on its soil under a cost-sharing pact. Once USFK decides to introduce THAAD batteries, Seoul’s burden-sharing could increase, according to defense sources.

Kim Jong-dae, a defense analyst with the minor opposition Justice Party, said under one scenario the USFK could pay for the first THAAD battery while the other unit is bought by the South Korean military.

"The issues of costs and sites for the THAAD deployment are expected to cause controversy domestically, as well as backlash from China," the defense analyst said.

China shows discomfort about the potential deployment of THAAD in South Korea.

Chinese Foreign Ministry spokesperson Hua Chunying said that even when pursuing their own security, countries "should take into account others' security interests as well as regional peace and stability."

Defense analysts said Beijing is particularly worried about the THAAD radar, an X-Band active electronically scanned array (AESA). If deployed, the land-based radar’s detection range could extend as far as 1,800 kilometers, meaning its coverage could reach well beyond North Korea and into China.

"THAAD deployment could bring a severe shock to the security status quo that exists between China and the US, as well as with Russia," said Chinese analyst Zheng Jiyoung of Fudan University.

Fighter Project Starts

South Korea began its multibillion-dollar project to develop an indigenous KF-X fighter jet over the next decade.

On Jan. 21, the Defense Acquisition Program Administration (DAPA) and Korea Aerospace Industries (KAI), main contractor for the KF-X program, held a meeting to launch the fighter development project.

KAI is supposed to develop six test fighters by 2021 before the full-scale development begins by 2026, according to DAPA officials.

"KAI will manufacture 120 fighter jets from 2026 through 2032 to replace the Air Force's aging fleet of F-4 and F-5 fighters," DAPA Commissioner Chang Myung-jin said.

Worth some $15 billion, the KF-X project is aimed at developing a twin-engine, 4.5 generation multirole fighter equipped with an AESA radar, which is much more advanced than the passive electronically scanned array radar currently in service.

Through an offset deal linked to South Korea's purchase of 40 Lockheed Martin F-35 Lightning II fighters in 2014, South Korea had sought 25 kinds of fighter technologies from the US firm, but Washington refused to permit the transfer of four of them, including the AESA radar technology. In the fallout, DAPA commissioned the state-run Agency for Defense Development to develop the radar and other key technologies with the help of local defense firms, such as LIG Nex1 and Hanwha Techwin.

Seoul and Washington are in negotiations, expected to take up to three years, for transfer of the other 21 technologies.