When President Trump says that if China doesn't help solve the North Korea problem, "we will solve the problem without them," or hints at rewarding Beijing if it makes Pyongyang behave, people understandably focus on what (if anything) that says about U.S. intentions.
Meanwhile, Vice President Pence's comments at the Demilitarized Zone Monday — emphasizing the American "resolve" demonstrated in Syria and Afghanistan, and saying that China needs to apply more pressure on Pyongyang — suggest that there's no real disagreement on goals, just on who will take the hard steps to get there.
But we should also ask what it would mean to "solve" North Korea from China's perspective and how likely it is that Chinese President Xi Jinping's government could do so.
Beijing has no affection for Kim Jong Un; the apparent murder of the North Korean leader's half-brother, Kim Jong Nam — who spent years in Macao and had good relations with Chinese officials — made a tense relationship worse.
China would prefer a denuclearized Korean Peninsula, especially if South Korea then gave up on deploying the U.S.-designed THAAD missile defense system. By contrast, an enlarged North Korean nuclear arsenal, likely to lead to further militarization in South Korea and Japan, conflicts with Chinese goals; war on the peninsula would be disastrous.
So Beijing is tightening some screws: refusing coal shipments (which earn North Korea scarce foreign exchange); talking about cutting off oil shipments, which would probably be devastating for Pyongyang; and arresting some people involved in smuggling.
But overall, China-North Korea trade — which accounts for 85 percent of Pyongyang's total trade — is up significantly from last year, despite Kim's provocations, and components recovered from some Korean missile tests suggest Chinese origins. Not surprisingly, some Americans see this as proving that Beijing must be pressed harder, so it will press harder.
It's not that simple — for some little reasons, and a big one.
Beijing's hard choices
Most of China's giant state-owned enterprises have scant involvement with North Korea; they have too many interests elsewhere to risk getting sanctioned in pursuit of limited profits. Smaller firms more often find smuggling worth the risk, and Beijing often cannot control them, because local authorities protect them.
This reflects something about China that many Westerners miss: The People's Republic is much less centralized in practice than it may appear to be. At any given moment, Beijing can set a few top priorities and get very impressive grass-roots enforcement of them — think, for instance, of compulsory birth control.
But the price of energetic local implementation on those issues is that Beijing looks the other way on many others. This arrangement is born of historical contingencies, but by now it is hard-wired into the system. Often Beijing even uses it positively, as it allows room for local experiments that can be disavowed if they fail.
But it also has much to do with the regime's endemic corruption, and with its slow response to widespread complaints about pollution, to name just two problems, which both reflect often close ties between local officials and profitable businesses. Hiding even basic data from superiors is common.
And once we see Beijing as having to make hard choices about the issues on which it will press hard for full compliance, it is not surprising that North Korean sanctions do not top the list.
Perhaps they would, some hard-liners suggest, if Beijing saw that Kim threatened its security as much as, say, corruption at home. And the bellicose talk on both sides of the dispute clearly has alarmed China. But that doesn't mean that weakening Kim is their preferred path forward.
North Korea's weakness as a strength
Here the bigger problem comes into view. Kim has the strength of weakness: that is, he can be uncooperative without worrying too much about being cut off, precisely because China knows his regime is vulnerable and does not want it to collapse. (The country does not face a famine like that of the 1990s, but cutoffs of strategic goods might cause a political meltdown.)
If Kim's government did fold, huge numbers of refugees would go to China. Even if a post-Kim transition was fairly orderly, it would very likely lead to a united, U.S.-allied Korea bordering China: also a very unwelcome prospect for Beijing.
And if the transition wasn't orderly — a more likely scenario — nightmares galore could follow. There would likely be a scramble among military factions for control of North Korea's existing nuclear weapons — which could easily draw in South Korean, U.S. and Chinese troops without clear lines to separate them, and/or lead some North Korean group that became desperate either to use the nukes before losing them or unleash the huge conventional arsenal targeted at Seoul. Further escalation might then follow.
In the longer run, while Beijing could live with a unified Korea that emerged peacefully and distanced itself from the U.S., it is hard to see how either of those conditions could be guaranteed. Thus preserving North Korea while hoping for some combination of reform, denuclearization and recognition — the path that seemed open for a while in the '90s — no doubt still strikes China as more promising than any scenario that involves enforcing truly comprehensive sanctions.
Kim knows this, of course, which means he knows that Beijing will probably not risk weakening him too much. It's a relationship Americans should recognize, since Washington has often helped sustain governments that it could not reform: South Vietnam and the Karzai government in Afghanistan are two particularly painful examples. Patron threatens to cut client's lifeline; client threatens to die; patron backs down; repeat periodically. For Kim, it's a risky game of chicken, but not a crazy one — apparently less crazy, in his view, than facing American hostility without a nuclear deterrent.
The analogy of Beijing's relationship with Pyongyang and Washington's relationship with Saigon is, of course, inexact — but not in particularly comforting ways. The South Vietnamese behavior that drove Washington did so because it prevented Saigon from ever winning the domestic support to stand on its own. Pyongyang, by contrast, still seems very much in control politically and can apparently survive much worse popular suffering than its people are experiencing right now. However, it poses a far greater threat to others than Saigon ever did.
The U.S., then, needs China to do better. But that requires jointly figuring out what mixture of carrots and sticks might work on Pyongyang itself, rather than expecting that Beijing will bring Pyongyang around for us if we just make it worth their while.
Kenneth Pomeranz is university professor of history and East Asian languages and civilizations at the University of Chicago and a past president of the American Historical Association. His most recent book is The Cambridge World History (2015), for which he co-edited the volumes covering the world since 1750.