Why China is pushing sanctions on North Korea — but still supports Kim Jong Un

North Korea conducted its fourth nuclear test way back in January 6, and the very next day the US and China began negotiating over what to do about it. China is North Korea's protector and sole ally, so expectations were low.

But this Wednesday, two months later, the UN Security Council unanimously approved a resolution, drafted by the US and China, punishing North Korea with some of the toughest sanctions in decades. A number of North Korean officials are sanctioned, and all cargo in and out of the country must be inspected, along with other measures.

So how big of a deal is this? China is indeed getting tougher on, and less patient with, North Korea. Their alliance is under some of the greatest strain it's experienced in years, and long-term trends suggest that strain will only worsen. Nonetheless, the fundamentals of that alliance remain in force.

As much as the US might like to hope there's a China–North Korea breakup coming — which would be a big deal, given that China's support enables North Korean bad behavior — there's little reason to believe this will happen. Big picture, don't expect the status quo to change.

The core Chinese strategy that explains what's happening

This all makes a lot more sense if you know China's longstanding policy toward North Korea, which, like many Chinese Communist Party policies, is often boiled down a very simple slogan.

In this case, it's just six words: "No war, no instability, no nukes."

In other words, China has three top priorities for the Korean Peninsula, and those priorities define everything. They're ranked in order, which is to say that China's top priority is to prevent war on the peninsula, its second priority is to prevent instability (for example, by way of North Korea's collapse), and third is to prevent nuclear weapons.

That helps explain why China is going to new lengths to punish North Korea for its January nuclear test (as well as a February missile test): It really wants to deter North Korea from further nuclear development, which it sees as bringing risks that could hurt China as well.

But it also shows why we shouldn't expect China to do anything as drastic as abandoning North Korea altogether. China wants to preserve stability and the status quo on the Korean Peninsula, with a divided Korea and a reliably anti-Western North Korea. Those are higher priorities than deterring North Korean nukes.

But there's still a real — if almost certainly temporary — breakdown in relations that led to these sanctions.

The odd story of how China–North Korea relations broke down

There's some evidence for a theory that says North Korea's nuclear test itself was driven, at least in part, by a breakdown in relations with China — a breakdown that has culminated in China's support for Wednesday's UN sanctions.

And that breakdown may have been precipitated by, bizarre as it may sound, a major diplomatic incident involving a North Korean all-female pop band. But it goes back to when Kim Jong Un first took power.

After North Korean leader Kim Jong Il died in late 2011, and his son Kim Jong Un took over, China took what analysts call a "wait and see" approach — watching the young and inexperienced new leader before deciding whether to support him.

In February 2013, as Kim Jong Un was still consolidating power, North Korea conducted its third nuclear test. Kim perhaps felt he needed to do this to prove himself to his country's military elite. This infuriated China.

"The Chinese were annoyed with the North Koreans over a lot of their behavior, not least the third nuclear test [in 2013], and had reduced the amount of assistance they were giving North Korea," John Everard, the former British ambassador to North Korea, told the BBC back in January.

"Through most of 2015, North Korea's relations with China — its sole ally and major economic benefactor — were distinctly frosty," Everard said.

But gradually, China's anger cooled, and besides, it looked like Kim Jong Un had consolidated his rule. It was time to make up. So in October 2015, Beijing sent a goodwill gift: Liu Yunshan became the first member of China's paramount leadership body, the Politburo Standing Committee, to visit North Korea since Kim had taken power.

That December, Kim sent a gift back. He announced the Moranbong Band, North Korea's state-run all-female pop band and Kim's pet project, would travel to China to perform a concert for Communist Party officials.

But December 10, 2015, is when it all came crashing down. The day the Moranbong Band arrived in Beijing, North Korean state media announced the country had developed its first hydrogen bomb.

Chinese leaders felt blindsided, seeing it as a cynical ploy to corner them into accepting the announcement. Senior Chinese leaders withdrew their attendance from the Moranbong Band shows, sending lower-level officials instead. The Kim regime, insulted and furious, canceled the shows outright. The Moranbong Band rushed onto a flight home, having not performed.

A couple of weeks later, North Korea tested its fourth nuclear device, perhaps in a deliberate act of defiance against Beijing.

"Significantly, before previous tests, North Korea has told the Chinese that they're about to test," according to Everard. "On this occasion, say the Chinese, they didn't."

The breakdown in relations was, if not a primary driver of North Korea's nuclear test, then at the very least, it would seem, a significant precipitating factor, as it left North Korea perhaps feeling less constrained by China's wishes. The fact that North Korea didn't give Beijing advance notice for the test makes it difficult to deny as much.

China is not abandoning North Korea

"For Beijing, the goal of sanctions is not regime change," Brookings's Paul Park and Katharine H.S. Moon write. This week's sanctions "are not robust enough or targeted enough to achieve regime change. If they were, China and Russia would not sign on."

The poison passing between China and North Korea is likely to dissipate. North Korea has never been a particularly pliant or reliable ally for Beijing. There is no reason to believe that China's calculus in supporting the regime has changed — and that may be part of why North Korea feels so free to defy its sponsor and only ally.

"China regards stability on the Korean peninsula as its primary interest," Eleanor Albert and Beina Xu, of the Council on Foreign Relations, write in a good backgrounder published last month. "Beijing has consistently urged world powers not to push Pyongyang too hard, for fear of precipitating a regime collapse."

This comes, most crucially, in lopsided trade that serves as a de facto Chinese subsidy of North Korea:

China–North Korea trade has also steadily increased in recent years: in 2014 trade between the two countries hit $6.39 billion, up from about $500 million in 2000, according to figures from the Seoul-based Korea Trade-Investment Promotion Agency. Recent reports indicate that bilateral trade dropped by almost 15 percent in 2015, though it is unclear whether the dip is a result of chilled ties between Beijing and Pyongyang or China’s economic slowdown. Nevertheless, "there is no reason to think that political risks emanating from North Korea will lead China to withdraw its economic safety net for North Korea any time soon," writes CFR Senior Fellow Scott Snyder.

There's a real irony here. Because North Korea is consistently and predictably irresponsible, and because China is more sensitive to the risks incurred by North Korean behavior, ultimately it may be China that works to mend ties.

"China’s strategic interests in stability and the denuclearization of the Korean peninsula will require Beijing to improve ties with Pyongyang in order to restore its leverage," Snyder, the CFR fellow, has written.

It's quite an ally that China's got there. But, in Chinese leaders' view, they don't really have another choice.