All About the US Missile Defense That’ll Protect South Korea---And Tick Off China

As South Korea builds up its missile defense, China keeps a close eye.
THAAD attives South Korea Airport
A truck carrying equipment need to set up the Terminal High Altitude Area Defense (THAAD) missile defense system arrives at the Osan base in South Korea on March 7, 2017.U.S. Forces Korea/Getty Images

North Korea's recent failed missile test was yet another reminder of why South Korea and the US would want to step up missile defense within the Hermit Kingdom's current weapons range. Recently, that's meant the deployment of a Terminal High Altitude Area Defense, a system that should help keep North Korea at bay---but is increasing tensions with China in the process.

The US delivered the THAAD to South Korea in March; it should be operational by the summer. In the meantime, it highlights the region's delicate diplomatic balance. It's also a clever bit of defense tech.

THAAD Company

THAADs are ground-based missile defense arrays, designed to disable medium and intermediate-range ballistic missiles. They're also portable, in this case mounted to the backs of armored vehicles. A THAAD has four main elements: a radar unit that surveils and tracks objects in the protected area and airspace, a truck-mounted launcher that fires interceptors and can be reloaded quickly, interceptors themselves (eight to a launcher), and a digital controller that runs the launcher and coordinates communication and data flow between the THAAD and other command centers.

THAADs target missiles on the way down, or in their terminal phase, but at a high enough altitude that the collision doesn't cause harm on the ground.

The US first began development of THAADs in the 1990s, though they didn't begin real-world testing until the 2000s; the Department of Defense conducted 13 successful THAAD tests between 2009 and 2013. South Korea's deployment will be the sixth; four are in the US, and another is in the US territory Guam. Additionally, the United Arab Emirates bought a THAAD from primary developer Lockheed Martin back in 2012. The US and South Korea announced in 2016 that the US would place a THAAD in South Korea to defend the country and US military assets against potential North Korean missile strikes.

“THAADs are tailored to those medium-range threats that North Korea has in spades---North Korea regularly demonstrates that kind of capability,” says Thomas Karako, the director of the Missile Defense Project at the Center for Strategic and International Studies. “THAADs are exactly the kind of thing that you would want for a regional area.”

The only downside? South Korea doesn't have enough of them. In fact, even when fully functional, the current South Korea THAAD "can’t even cover Seoul, let alone catch Chinese missiles going to the US," says Bruce Bennett, a senior defense analyst at the RAND Corporation. Because the THAAD has a relatively small interceptor range of around 125 miles, it would take two or three of them to cover all of South Korea. Still, the country having some protection against a potential North Korean strike beats having none. Just not if you're China.

Delicate China

Chinese officials expressed anger over the THAAD in March, with one spokesperson promising that China would “take the necessary steps to safeguard our own security interests, and the consequences will be shouldered by the United States and South Korea.”

It's unclear what China's main concern stems from. It could be the THAAD's radar, which from so nearby in South Korea could potentially track China's own missile program. But US radar systems in Japan can already see into China, as can ships in the region, and various satellites. Meanwhile, concerns that the THAAD is being placed in South Korea in anticipation of potential Chinese military action agains the US or its allies seems similarly unfounded; a THAAD only intercepts medium-size missiles on their way down, not intercontinental missiles early in their flight.

"Chinese missiles going to Japan would fly too high over South Korea for the THAAD to be able to intercept them," says Bennett.

Citizens protest outside a golf course being used as the site for the recently installed THAAD system, in Seongju on March 18, 2017.

ED JONES/AFP/Getty Images

Nonetheless, the cybersecurity firm FireEye said this week that China has been upping its cyber attacks on South Korea recently, corresponding to when THAAD deployment began.

"China cares deeply about it primarily I think for political reasons. The Korean peninsula is very close to them and I think it offends their sensibilities to have another symbol of American presence there," says Karako. "And also in a more tactical sense this is something that will drive the United States and South Korea closer together and China ultimately doesn’t really want that."

Regardless of the motivations, both South Korea's THAAD and China's objections to it continue apace, making a volatile part of the world that much more so, even as the THAAD makes part of it more safe.