TOKYO (AP) — China's announcement it has suspended North Korean coal imports may have been its first test of whether the Trump administration is ready to do something about a major, and mutual, security problem: North Korea's nukes. While China is Pyongyang's biggest enabler, it is also the biggest outside agent of regime-challenging change — just not in the way Washington has wanted.

Judging from Trump's limited comments so far, and the gaping chasm between Washington's long-held focus on sanctions and punishment and Beijing's equally deep commitment to diplomatic talks that don't require the North to first give up its arsenal, a deal between the two won't come easily.

But if Beijing is indeed sending a signal to Trump about Pyongyang, its opening bid was a big one. North Korea's coal exports to China totaled $1.2 billion last year, according to Chinese customs. U.S. officials say that represents about one third of the North's total export income.

For Kim Jong Un, that's going to hurt.

In a bitter critique, the North's official media on Thursday likened the decision by Beijing to an enemy state's move "to bring down" their social system and, in a tone it normally reserves for Washington, Tokyo or Seoul, accused Beijing of "dancing to the tune of the U.S." It was one of the most biting attacks the North's media has ever made against China.

Trump, meanwhile, has often appeared to be more interested in bashing China than dealing with it. He has accused Beijing of not helping at all with the problem, and at the height of his bombast last year on the campaign trail, claimed China has "total control over North Korea."

"China should solve that problem," he said. "And if they don't solve the problem, we should make trade very difficult for China."

Trump has vowed to "deal with" North Korea and his administration is conducting a broad-ranging policy review, including how to make sanctions bite. Negotiations haven't been ruled out, said a U.S. official who wasn't authorized to discuss internal deliberations and demanded anonymity.

Trump's basic position reflects a dusty old chestnut in Washington: that China can, and should, force Pyongyang to abandon its nuclear weapons but has instead, recklessly and shortsightedly, become North Korea's great enabler because it fears South Korea, an American ally that hosts U.S. troops, controlling everything right up to its border.

That is, after all, why China fought the U.S. in the Korean War.

But the pervasive Chinese economic engagement with the North that so aggravates sanctions' advocates in Washington has dramatically advanced the growth of a gray-zone market system, the swelling of an increasingly influential merchant class that is not utterly beholden to Kim Jong Un or his ruling party and shifts in popular attitudes and social relationships that could be extremely destabilizing for the entrenched North Korean status quo.

Beijing is no buddy of the Kims. And both sides know it.

Though they fought on the same side in the 1950-53 Korean War, which cost China hundreds of thousands of lives, neither side trusts the other or harbors any illusions their relationship is, or ever was, anything like a friendship.

On the flip side, protecting stable trade relations with a prosperous Seoul is far more important and profitable for Beijing than its dealings with the Kims' northern dynasty. That trade serves to keep Pyongyang in check and also undermines the assumption a reunited Korea would have the same motivations to remain the stalwart ally of Washington that Seoul now is.

It's also not a given the Korean public would continue to support the idea of hosting U.S. troops at all since their only purpose post-unification would, indeed, be to threaten China. There is considerable popular opposition in the South to the U.S. bases there even with the North intact and growing stronger.

Exasperated U.S. policymakers like to say there are no good options with North Korea.

China could make the same complaint.

Beijing is as painfully aware its influence over Pyongyang has limits as Washington is aware that its military superiority alone cannot solve the problem.

China also knows the impact of a North Korean implosion — regional economic chaos, huge flows of refugees into its relatively poor northeast, which already has a sizable ethnic Korean minority — are far bigger problems for it than for the U.S. and far more likely than a last-breath, suicidal nuclear attack by Pyongyang on Washington.

Seen in that framework, it isn't surprising China has half-heartedly gone along with U.N. resolutions on the North's nuclear program while advocating for enough security on the peninsula for U.S.-North Korea diplomacy to be a viable option. Its suspension of coal imports was done to comply with an import cap that was part of sanctions it agreed to last year — when Trump was still a private citizen.

But Beijing is also clearly tired of being scapegoated by Washington.

Repeated, self-righteous demands from the White House for China to take sole ownership over what Beijing considers to be a mess Washington created by rushing across the 38th parallel and on to the Yalu River when the North Korean army was in full retreat nearly 70 years ago almost guarantee it won't.

At least not in the way that Washington wants.

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Talmadge has been the AP's Pyongyang bureau chief since 2013.