I typically hear two main justifications offered for China's support of North Korea: collapse of the DPRK would result in one or both of

  • A refugee crisis as displaced North Koreans seek asylum in China
  • One way or another, the establishment of a government friendly to the US on China's borders

For example, this article, cited in this Po answer.

I have a hard time following the logic behind the second reason. The only issue I can see in sharing a border with a US-friendly power is vulnerability in the event of a ground invasion of Chinese territory. The only circumstance I can conceive of that would involve a major act of aggression on China's part against the territory of a neighbor. Even then, it seems unlikely.

Is there some other reason why a "buffer state" is important?

  • 2
    Especially with the knowledge that you should "never get involved in a land war in asia"
    – discodane
    Aug 16, 2017 at 18:54
  • 7
    Perhaps you have more trust in the benignity of the US military than China does.
    – user9389
    Aug 16, 2017 at 19:12
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    Right now, US-friendly south Korea or US-friendly united Korea does make less difference than before. If US wanted to, deploying advanced weapon system like early-alart radar, B2, F22, missile and missile defence systems, or even navy bases, air force bases at South Korea is just as effective as near the border. So truthfully there is indeed some old-time thinking going on. I guess now divided Korea still have the advantage that China can use NK to voice a threat to SK and US, most countries other than NK rarely directly threat another country. Aug 16, 2017 at 19:26
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    For the same reasons the USA were against having a pro-USSR Cuba so near to their shores.
    – MasB
    Aug 17, 2017 at 0:03
  • This question is wrong I think because once North and South Korea have become one country the US will not have any more excuses to keep its forces in Korean peninsula unless US government finds another excuse to justify US troops presence in Korean peninsula. Because right now their excuse is if US troops leave North Korea will invade and occupy South. So in case of North-South merger US forces will have to leave and they will have no way to spy on China from close border. Therefore it is actually Americans who don't want North-South merger as it is harmful to them.
    – Rolen Koh
    Jan 15, 2018 at 9:54

5 Answers 5



Who are you less likely to appreciate as a neighbor--the one right next door to you who blasts music until 3am, or the one two doors down doing the same? If both exist you're likely to not appreciate either of them, but if you had to pick the lesser of two evils, you'll likely pick the one living two doors down.

The same applies here. China can safely ignore the US and its relationship with South Korea because the direct neighbor (and most likely to be impacted by any tensions or border disputes) is North Korea, not China. If instead China shared a border with South Korea, suddenly the US is that much closer and annoying to China in a metaphorical sense.


You acknowledge the ground component of the US having an ally right on China's border, but you're not considering the air and sea side of things. If the US or SK made any kind of threatening gestures towards China, you can rest assured North Korea would 'misinterpret' (remove quotes as necessary) the move and strike down the invaders, saving China the bad optics and allowing a bad guy to continue being the bad guy. If instead the US was able to maneuver right next to Chinese territory without NK as a buffer, it would be much harder to deny that they were the ones to fire missiles since, well, they would be the only ones who would in that area.


   There a 3 major reasons :

  1. Control and surveillance of Chinese territory. If you look at the map, North Korea is very close to strategically important port of Dalian and Bohai Sea. Later is home of some important PLAN(Chinese Navy) assets like strategic ballistic submarines. US control of North Korea would also enable them survey lot of Chinese territory without need to actually cross border. It is worth to mention that even capital Beijing is not so far away.

  2. Cross-border raids with "freedom fighters". Usual US tactics is to train ad equip rebel groups, and then let them attack across the border. This was seen dozen of times (Iraq, Yugoslavia, Libya , Syria, even attempted against Russia in Chechnya and latter in Ukraine). It is quite possible US would try same tactics of "spreading democracy" with China, with safe heaven for insurgents in North Korea.

  3. Hostile country across border . Even if US doesn't attempt anything directly, Korea aligned with US would always force Chinese to dedicate substantial military capability to that sector. This of course drains resources, and prevents them to project power elsewhere.

  • even capital Beijing is not so far away not in Chinese terms, no; for the rest of us, it's ~800km away, which is the extension of a few large European countries :) Dec 14, 2017 at 6:59

You wrote:

The only issue I can see in sharing a border with a US-friendly power is vulnerability in the event of a ground invasion of Chinese territory.

Sharing a border can be an issue even without a ground invasion. It can easily be used to make threats of invasion, or to spy on them...

Moreover, it is true that China is already threatened by South Korea, but there is an equilibrium with North Korea, which would disappear in this line of events.

You also wrote:

The only circumstance I can conceive of that would involve a major act of aggression on China's part against the territory of a neighbor. Even then, it seems unlikely.

For this kind of problem, you cannot focus on next year. Any such decision have consequences over 50 years, and often over centuries. It is not wise to assume that an invasion is impossible because it is unlikely now. Moreover, China will not give something to the US without getting anything.

  • Point take on short-term vs long-term. I'm curious if you can cite anything to support the idea that a land border makes spying easier (outside of remote surveillance of activities within some miles of said border -- or perhaps that's all you meant).
    – reo katoa
    Aug 16, 2017 at 22:40
  • I meant that. But perhaps some times you need to have physical access to your spies (to give them something that cannot safely be sent) and then it may be easier to have a physical border. Or if someone wants to flee... I'm not saying any of these is really important, but still it is not nothing. You can also think about what happened in Crimea.
    – Distic
    Aug 16, 2017 at 22:49

One theory is that if the DPRK collapses, it will be absorbed/annexed/folded into South Korea. Then South Korea and China would have a long border together.

South Korea is a US ally and currently hosts US personnel and equipment and participates in exercises with the US, and the assumption is that these US assets would then be in closer proximity to China under a S.K.-dominated united Korea.

A precedent for this is Germany. East Germany basically folded into West Germany, and now unified Germany - a strong US ally with enormous US military presence - was now that much closer to Russia.

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    That much is clear, but the heart of my question is why it would matter. Yes, the US assets would be in closer proximity, but it's not like the US couldn't strike China from SK now, and I'm not seeing a plausible scenario in which that proximity makes an invasion likely.
    – reo katoa
    Aug 16, 2017 at 19:33

China's official stance is that it does not like catastrophic change of DPRK's regime but has no problem with peaceful transitions. Military solution can solve America's problem but will leave a huge mess behind and will very likely create humanitarian crisis on both sides of the borders.

The other answers presumed unreasonable fear. China's diplomatic circle is well aware of the fact that American influence upon East Asians are overall beneficial. It also has a mellowing effect upon the East Asian character. Nowadays neither South Koreans nor the Japanese are warlike. Pakistan was America's staunch ally throughout the cold war, yet Pakistan's conduct toward China was nothing but friendly; India was anti-America in the 50s and 60s, yet it was India who conducted spy and espionage and naked invasions against the Chinese.

Further more, Americans upon contact with China tend to become Sinophiles for life. Most of these people are what we consider "hard-line" conservatives today, among whom the most distinguished representatives are Arthur Henderson Smith, John Leighton Stuart, George Marshall and George H. W. Bush. It is very likely that US soldiers stationed on the border will be converted into Sinophiles by the legion.

All of China's top three universities today were founded and financed by Americans more than 100 years ago when China was weak and defenceless.


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