South Korea is edging closer to the long-term deployment of the Terminal High Altitude Area Defense (THAAD) anti-ballistic missile defense system, a controversial move that threatens to stoke tensions with China and North Korea.
This month, Jane’s reported that South Korea’s Ministry of Environment (MOE) had completed an environmental impact assessment (EIA) of the US Army’s THAAD temporarily deployed at Seongju, 215 kilometers southeast of Seoul.
“As the MOE and the MND have completed the environmental impact assessment of Seongju base in cooperation, we will closely cooperate with the US to faithfully reflect the consultation opinions and proceed with the project,” said the MND in a statement cited by Janes.
THAAD’s deployment in South Korea generated considerable controversy in 2017, with then-president Moon Jae-in accusing the MND of failing to report the system’s arrival in the country. There were also domestic complaints of a lack of an EIA assessment and backlash from locals fearing high electromagnetic wave (EMW) exposure.
Meanwhile, China complained that the system could neutralize its nuclear deterrent and responded with a series of measures to punish Seoul. Tourism dropped by about 40% and many Korean consumer goods and cultural products were boycotted inside China
Missile Defense Advocacy Alliance notes that each THAAD battery includes a launcher, interceptors, radar and fire control unit. The source mentions that the highly-mobile truck-mounted launcher can carry eight hit-to-kill interceptor missiles with 200-kilometer ranges.
It also says that the system’s Army Navy/Transportable Radar Surveillance (AN/TPY-2) radar can search, track and discriminate objects up to 1,000 kilometers away and provide tracking data to the interceptor missiles, with the fire control unit integrating all system elements.
The Institute of Security and Development policy notes that one of THAAD’s main characteristics is its transportability, which makes it easy to reposition the system.
The source mentions that feature gives THAAD flexibility to respond to changing threats, unlike the Aegis and Patriot missile systems, both of which have limited mobility.
It also says that THAAD can intercept both exo- and endo-atmospheric threats at a regional level, unlike Aegis, which can only intercept exo-atmospheric targets, and Patriot, which can only hit endo-atmospheric threats at point defense ranges.
However, THAAD also has its limitations. Asia Times noted in December 2022 that North Korea has been practicing highly-lofted trajectory missile launches to increase the chance of penetrating missile defenses such as THAAD.
Such launches result in a high terminal velocity for ballistic missiles, undermining the effectiveness of missile defenses. However, that launch significantly reduces the missile’s range, as most of its fuel is spent on reaching a high angle instead of covering great distances.
In such an attack, missile defense radars lose track of the target when the latter reaches its apex, then regain track of the hostile missile too late for interceptors to destroy. Also, as interceptor missiles fly against gravity, it is harder to catch up, correct course and hit the constantly-accelerating target at the right angle.
Adam Taylor notes in a 2017 Washington Post article that THAAD may be of limited use against North Korea as it could not take down the latter’s numerous short-range tactical ballistic missiles (SRBM) and artillery rounds that do not reach such high altitudes.
Instead, Taylor says that THAAD’s radar capabilities may be the reason behind its 2017 deployment to South Korea. He says that THAAD’s sophisticated radar could be used to track China’s missile systems, potentially giving the US an edge over China in a future conflict.
Li Bin notes in a 2016 Carnegie Endowment for Regional Peace article that THAAD’s AN/TPY-2 radar can undermine China’s nuclear deterrent by collecting essential data on Chinese nuclear warheads that the US could not acquire from other sources.
Bin mentions a missile warhead is usually cone-shaped and has a very smooth surface on the front and sides, reducing its frontal radar cross-section.
However, he says that’s not the case for the rear of missile warheads, with uneven surfaces giving that part a much larger radar cross-section.
Bin notes that the THAAD system to be deployed in South Korea could be in an exceptional position to view the back of Chinese nuclear warheads. He mentions two scenarios where THAAD can be used to gather intelligence on China’s missile arsenal.
First, Bin says that THAAD can gather intelligence on China’s missiles when the latter conducts flight tests in northeast China to develop missile defense countermeasures. He notes that intelligence gleaned by THAAD could be used to differentiate between decoys and actual warheads.
Second, Bin says that THAAD could track incoming Chinese ballistic missiles fired from Central China at a very early stage and relay their trajectory to the US national missile defense system. He mentions that would give the US more time and potential attempts to intercept an incoming Chinese nuclear warhead.
Such scenarios, Bin says, may force China to change the target points of its missile tests in the East China Sea, sparking threat perceptions in South Korea, which neither party desires. Apart from the East China Sea, China may use the South China Sea as an alternative launch area for missile tests and secondary strikes.
Asia Times reported in November 2022 that China had fielded its new JL-3 submarine-launched ballistic missile (SLBM) with a 10,000-kilometer range on its Type 094 nuclear ballistic missile submarines (SSBN), giving it the capability to hit the US from protected bastions in the South China Sea.
Previously, China’s SSBNs with the older JL-2 missile with a range of just 7,200 kilometers needed to travel into the waters west of Hawaii to launch their SLBMs, passing chokepoints such as the Miyako Strait and Bashi Channel, making them vulnerable to US and allied anti-submarine forces.
In addition, Asia Times reported in April 2023 that China is now maintaining round-the-clock SSBN patrols in the South China Sea, ensuring a second strike capability against the US.
JL-3-armed Type 094 SSBNs are now operating from Hainan to the South China Sea, showing China’s rapid improvement in logistics, command and control, and weapons to maintain a credible sea-based nuclear deterrent.
That development also indicates that China is deploying its SSBNs similar to established nuclear powers such as the US, UK, France and Russia.