How North Korea's Rocket Launch Could End Up Screwing China in a War Against the US

North Korea took one small step for its scrappy little space program and one giant leap toward further isolating itself from the rest of the world on Sunday when it once again violated UN resolutions by launching a long-range rocket that carried a satellite into orbit.

Officially, the satellite, dubbed Kwangmyongsong-4 ("Bright Star-4") after a poem written by late leader Kim Jong-il, is for Earth observation purposes, a vague designation that can cover everything from meteorology to urban planning to reconnaissance. The only thing publically known in the West is that the satellite has been accurately placed in a very specific orbit well-suited to Earth observation tasks. South Korea's spy agency reportedly thinks it's just a hunk of space junk that serves no real purpose.

The bigger concern is that North Korea, which just tested what it claimed was a hydrogen bomb in January, is using its space program as a cover for developing ballistic missile technology that could conceivably be used to drop a nuke on the West Coast of the United States. In response, there's been renewed talk about the US ignoring objections from China and putting interceptor missiles in South Korea that could shoot down any ballistic missiles launched by Pyongyang.

On Monday, the Pentagon said it hoped to deploy the Terminal High-Altitude Area Defense (THAAD) anti-missile system to South Korea as soon as possible, and that the system could be in place in two weeks if negotiations go smoothly.

"Without getting into a timeline, we'd like to see this move as quickly as possible," Pentagon spokesman Peter Cook told news agency AFP. "We are beginning the consultations now and in the current days with the South Koreans, and we expect that this will move in an expeditious fashion."

Whether it's really necessary to put the THAAD system in South Korea is up for debate — and it might have more to do with China than North Korea.

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For starters, North Korea's long-range rocket, the Unha-3, kinda sucks as an intercontinental ballistic missile (ICBM). It's launched from a vulnerable above-ground, rocket gantry rather than a silo hardened against attack. Fueling the rocket with its explosive, toxic, and corrosive propellant takes a couple days — a period when it's just sitting out there on the launch pad, extremely vulnerable to long-range missile attack.

There are only a handful of launch sites that can handle the rocket, so it wouldn't be hard for the US or South Korea to take out all of those vulnerable targets at a moment's notice. It would be possible, in theory, for North Korea to load up a couple rockets in advance and launch them as soon as the fighting breaks out. But if there's a war already underway, those launch sites are toast. Overall, that means the Unha-3 doesn't have much meaningful capability as a strictly military weapon, though some suspect it's being used strictly to test the technology.

If you assume the North Koreans have been doing their homework on making a nuclear warhead small enough to fit on the rocket, the successful launch of Unha-3 could be the indicate Pyongyang has the ability — or could soon — to kick off a major war with a series of nuclear strikes against major US military bases in South Korea, Guam, Hawaii, and maybe even the West Coast. But nobody thinks the North Koreans are crazy enough to use a surprise nuclear attack as their opening salvo in a war against a country able to hit back with hundreds of nukes.

But even if the North Koreans decided to start a game of global thermonuclear war, the US deployment of THAAD has precious little bearing on Pyongyang's potential use of the Unha-3 as an ICBM. That has more to do with how THAAD works than with anything Kim Jong-un's regime might have up its sleeve.

Watch the VICE News documentary Launching Balloons into North Korea: Propaganda Over Pyongyang:

Shooting down incoming ballistic missiles is extremely difficult, and military planners generally want to take several shots at an incoming warheads just in case they miss a couple times. That's what missile folk call "layered defense." THAAD is a new system, intended to add a longer-range, more capable interceptor to that layered defense, augmenting existing systems. If all goes according to plan, THAAD is supposed to hit incoming warheads just as they're reentering the atmosphere, at altitudes of up to 150 kilometers (90 miles) and ranges of 200 kilometers (120 miles). The system is cued by radar technology that's capable of picking out targets at least 1,000 kilometers (600 miles) away.

Right now, THAAD is just about shooting at missiles, but it wouldn't be impossible to add the ability to take on aircraft at a distance. If you can hit an incoming ballistic missile, shooting an aircraft out of the sky isn't out of the question.

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South Korea and the US forces in the Korean peninsula have already deployed systems capable of shooting down short- and medium-range ballistic missiles. Those existing systems are pretty good at covering a single area, like an airport, or particular neighborhood, but those shorter-range systems start running into problems if they're being used to cover an entire city, especially against long-range ballistic missiles, which have higher approach speeds that reduce reaction time.

But both existing systems and THAAD are all about hitting incoming warheads just before impact. It doesn't do the US any good to have THAAD shoot at a missile launched from North Korea that is bound for Hawaii or Seattle because the geometry is all wrong. The THAAD missile would try — and fail — to catch up with an outbound ICBM already on its way across the Pacific.

Until now, South Korea has been pretty lukewarm about THAAD. China, on the other hand, has been very clear that deploying THAAD to the Korean peninsula is not something it would be happy about. In fact, Beijing has been so touchy about THAAD that some claim it's actually been having the opposite effect, encouraging South Korea to take a closer look at the program.

Either way, domestic political pressure is the reason that Seoul is putting THAAD back on the table despite its ineffectiveness in preventing an attack. There's only so many times the North Koreans can detonate nukes and launch stuff into space before someone in South Korea demands that somebody do something. Given that the other option is for South Korea to launch airstrikes on North Korean launch facilities — almost certainly igniting an all-out war — it's pretty benign for Seoul to suddenly get enthusiastic about THAAD.

What's more intriguing is that THAAD could make things a whole lot more interesting if the US and China ever find themselves squaring off in a full-scale conflict. South Korea's existing air defense and anti-missile systems are short enough range that they're only really relevant in a close-up fight with an immediate neighbor like North Korea. But THAAD units could be turned toward China, providing radar coverage several hundred miles into the Chinese mainland and limited missile coverage along the Korean coast.

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China has been developing hypersonic glide weapons to defeat missile defenses, but there's a proposed upgrade to THAAD designed specifically to address this threat: THAAD Extended Range (THAAD-ER). The proposal is in its early stages, and while it wouldn't necessarily stop hypersonic glide weapons cold, it's by far the least crappy option. Extending the range of THAAD substantially would give those air defense batteries the capability to shoot down anything coming out of China and keep tabs on anything flying over China.

And this points to China's bigger concern about THAAD: They're afraid that it could be used as part of a larger regional missile defense network, potentially neutralizing their nuclear deterrent. The ocean between Korea and China includes a key bit of water called the Bohai Sea, which is thought to be a Chinese naval bastion. It's basically a place where Chinese submarines equipped with nuclear missiles can hide without fear of being hunted by enemy aircraft because China's land bases are close enough to keep them covered.

Because of the geometry and distances involved, there's no way a Chinese ICBM launched from the Bohai Sea could be intercepted by a THAAD-type system based in South Korea. But a long-range THAAD-ER battery might provide cover for sub-hunting aircraft. And even if THAAD-ER missiles didn't have enough reach to cover the Bohai Sea, the radar almost certainly would, allowing the US to monitor test launches and gain valuable intelligence.

Alternately, if everything went completely to hell and China was inclined to launch its submarine-based missiles, it's conceivable that THAAD radar could detect those launches and alert the US anti-ballistic missile installations in Alaska, giving them more time to spot and shoot down the incoming Chinese missiles.

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To make a long story short, if China and the US ever found themselves in a major war, THAAD systems based in South Korea could end up being a key strategic factor. Of course, there's no requirement that says Seoul would have to get involved in that fight, which would pit its biggest military ally against its biggest trading partner. And that raises the question: Why would South Korea start fooling around with things that could drag them into a such a war?

Conventional wisdom says that if anyone is capable of talking some sense into the Kim regime, it's Beijing. And if China can't keep North Korea in check — which increasingly appears to be the case — that makes South Korea a bit nervous. Perhaps Seoul sees THAAD as a bargaining chip to make China push Pyongyang a bit harder. Or perhaps the South Koreans just realize that THAAD would give them a lot of leverage regardless of who starts shooting whom.

Follow Ryan Faith on Twitter: @Operation_Ryan

Photo via US Missile Defense Agency