President Donald Trump still seems to think that pressuring China to rein in North Korea's Kim Jong-Un is the best way to push back against the rogue state's nuclear expansion, most recently in the form of testing an intercontinental ballistic missile that could reach Alaska.
This approach hasn't worked so far, and there's a reason: Chinese President Xi Jinping has no strong reason to object to a North Korean nuclear insurance policy against the threat of being overthrown by the US
China values regional stability, which is good for trade. It doesn't want a nuclear war in its backyard. But it couldn't possibly benefit from the collapse of Kim's regime, which would almost certainly leave a US ally, South Korea, in charge of a unified Korea across the border. China also knows that the US can't realistically attack North Korea because of the loss of South Korean and American lives that would follow.
The result is that China doesn't lose much as North Korea gets stronger. And it gains strategically as its own buffer state becomes still more impregnable.
To understand how this geopolitical game is playing out, start with Trump's efforts thus far. He began by drawing attention to North Korea's aggressive stance, which shouldn't have surprised him. North Korea wants to be noticed. It wants to test the new administration's will. And it wants to teach the new US government the lesson that it can't do much in the face of a nuclear power.
Trump responded by turning to China. He tweeted that China would benefit from a generous new trade deal with the US if it would "solve the North Korea problem."
Nothing happened. China didn't have much to gain, since its leverage on a trade deal with the US is already strong, and Trump was vague about the benefits. Trump accordingly tweeted his frustration that China hadn't helped.
This unfortunate sequence sent North Korea the signal that Trump was realizing there wasn't much he could do. It responded by continuing to test missiles. Finally, it got the ICBM to work, a major success for a regime that often flubs its missile tests.
Trump again directed his attention to China -- this time by threatening rather than offering a sweetener. He tweeted that the US shouldn't trade with countries that don't help it, and noted a supposed rise in China-North Korea trade, which itself could actually be a sign that Beijing was trying to deepen its ties with Pyongyang to gain leverage.
The US ambassador to the United Nations, Nikki Haley, also took a stab at pressuring China. She threatened to propose new U.N. sanctions against North Korea to the Security Council. That would put China in the embarrassing position of having to exercise its Security Council veto to block the move.
North Korea has no incentive to back down. It's interest is to acquire the weaponry it needs to be safe from external attack. Its nuclear capability serves that end by buttressing its threat to use conventional weapons against Seoul.
If North Korea had a regime that benefited from regional and global trade, it might be possible to negotiate a deal that delays the acquisition of the weapons, much as the administration of President Barack Obama did with Iran. Because the Islamic Republic hadn't yet developed a proper nuclear strike capacity, it had a further incentive to enter an agreement.
But North Korea doesn't participate meaningfully in the global economy, except through trade with China. Its founding philosophy, juche, is essentially a form of autarkic self-reliance. So North Korea isn't susceptible to positive incentives from abroad.
China, in contrast, wants to be a responsible global actor and wants to avoid the regional instability that would come from a war. Trump's mistake is to think that translates into a motivation to do its bidding on North Korea.
China knows that the endgame from a Western perspective is regime change in Pyongyang. That would probably lead to reunification of the two Koreas. With thousands of US troops stationed in South Korea, that would be dangerous from China's perspective.
Xi is in the process of expanding China's regional and global strategic position. The last thing he wants is to give the US a chance to make a counter-move. For that reason, he needs North Korea to remain stable.
So don't expect Trump's threats to work any better than his blandishments.
The only thing that would move China would be the credible threat of war in the Korean peninsula. But Xi can be reasonably sure Trump won't go that far. Such a war would be wildly costly in terms of South Korean lives and those of US personnel in the region.
As my Bloomberg View colleague Eli Lake has put it, the US choice is now concession or war. Expect concession – just don't expect the Trump administration to call it by its real name.
Noah Feldman is a Bloomberg View columnist. He is a professor of constitutional and international law at Harvard University and was a clerk to US Supreme Court Justice David Souter. His seven books include Cool War: The Future of Global Competition/