President Trump’s two-part tweet Saturday, coming after his June 20 tweet, signals nothing no less than a reversal of four decades of U.S. China policy.

At about the same time, America’s ambassador to the U.N., Nikki Haley, indicated the time for diplomacy with regard to North Korea is at an end. Moreover, with Senator Dianne Feinstein’s comments Sunday, the frustration with China is now evident across the U.S. political system.

And so it looks as if North Korea is driving American foreign policy in directions not seen before.

Saturday evening the American leader ripped Beijing with this: “I am very disappointed in China. Our foolish past leaders have allowed them to make hundreds of billions of dollars a year in trade, yet .  .  . they do NOTHING for us with North Korea, just talk. We will no longer allow this to continue. China could easily solve this problem!”

Trump’s tweet will be long remembered. Since Nixon’s groundbreaking trip to Beijing, the integration of China into the international system has been one of the highest priorities of American foreign policy. Washington policymakers accepted unfriendly and even dangerous behavior from Beijing for fear of angering the Chinese. The rationale was that eventually China’s policymakers would see it in their interest to work with the U.S. in supporting the international system.

The American strategy, unfortunately, only fed the sense of self-importance of the Chinese, who then took advantage of their U.S. counterparts. They used American patience to, among other things, support the North’s ballistic missile program with equipment and almost certainly technology.

Trump, after the early-April meeting at Mar-a-Lago with Chinese ruler Xi Jinping, looked like he was going to continue Washington’s four-decades-old approach, trying to buy China’s cooperation with concessions—and placing friendly China relations above disarming the Kim regime.

Xi, post-Mar-a-Lago, began to help on North Korea, for instance leaning on Pyongyang to not detonate the nuclear device that had already been buried at its Punggye-ri test site.

The Chinese, however, did not curtail other support, especially assistance to the North’s economy. China’s two-way trade with its North Korean neighbor was up 10.5 percent in the first half of this year. Moreover, there are no indications that Beijing tried to slow down the North’s ballistic missile efforts. So far this year, Pyongyang has launched 18 missiles in 12 tests.

The July 4 launch was the first flight test of an intercontinental ballistic missile. Friday’s test demonstrated that the two-stage Hwasong-14, by staying aloft for maybe as long as 47 minutes, could reach Chicago and perhaps New York.

Furthermore, the North Koreans, in all probability, will soon test their longer-range, three-stage KN-08, as Bruce Bechtol of Angelo State University has predicted, and possibly conduct an atmospheric detonation of a conventional explosive to demonstrate the effectiveness of their heat shielding. Once the North perfects heat shielding—something it has almost certainly accomplished—the regime will have all the technology it needs to hold America at risk.

In sum, the North Koreans may be able, in less than a year, to land a nuclear warhead anywhere in the continental United States.

Time, therefore, has become a factor. Trump first indicated his impatience on June 20. “While I greatly appreciate the efforts of President Xi & China to help with North Korea,” he tweeted, “it has not worked out.”

Soon after, on June 29, he had the Treasury Department declare a small-fry Chinese bank, Bank of Dandong, a “primary money laundering concern” pursuant to the Patriot Act, essentially cutting it out of the global financial system. On the same day, Trump notified Congress of a $1.42 billion arms sale to Taiwan, something that “outraged” Beijing.

Those and other measures were warnings that the administration could impose even more costs on China. Trump met Xi on the sidelines of the G-20 in Hamburg at the beginning of this month, and there the American leader spoke the language of cooperation, but the friendly mood did not last. On July 19 the Trump administration broke precedent by letting trade talks, the U.S.-China Comprehensive Economic Dialogue, collapse. There was no attempt by Trump officials to hide the failure, another break from past practice.

Cooperation no longer seems to be on the menu and neither is engagement, the policy approach of the Nixon, Ford, Carter, Reagan, Bush, Clinton, Bush, and Obama administrations. Trump’s tweet Saturday evening questioned the bedrock of U.S.-China ties, trade. And the president’s tone was acidic.

China, unfortunately for Washington, calculates its interests in ways fundamentally different than the way America does. And it is not only Beijing’s support of North Korea that divides China and the United States. China’s attempts to grab territory of neighbors and dominate its peripheral seas challenge the basis of an orderly, rule-bound international system, and so do Beijing’s cyberattacks against American networks, its attempts to undermine the concept of human rights, and the closing off of its markets to foreign competitors.

Trump, therefore, gets credit for asking why the U.S. should trade with—and therefore strengthen—a system that is at odds with America’s conception of the world.

In the meantime, the frustration with China over North Korea is evident. On Sunday, Senator Feinstein scolded Beijing on CBS’s Face the Nation and Ambassador Haley reinforced Trump’s message of impatience with a tweet of her own, saying the administration is “done talking about NKorea.”

And to reinforce the point, she denied rumors she had called another U.N. Security Council meeting. “An additional Security Council resolution that does not significantly increase the international pressure on North Korea is of no value,” she said in a statement Sunday. “In fact, it is worse than nothing.”

A week ago, General Joseph Dunford, chairman of the Joint Chiefs of Staff, said he was willing to give diplomacy only “a few more months.”

America’s diplomats, evidently, are even less patient than that.

Gordon G. Chang is the author of Nuclear Showdown: North Korea Takes On the World.  Follow him on Twitter @GordonGChang.