In a Tuesday announcement at the White House, President Trump withdrew the United States from the nuclear deal with Iran. "We cannot prevent an Iranian nuclear bomb under the decaying and rotten structure of the current agreement," he said. "Therefore, I am announcing today that the United States will withdraw from the Iran nuclear deal."

This sends a powerful signal to the rest of the world, most especially close U.S. allies: America is a deranged, crumbling basket case of a nation that can't be trusted to understand elementary logic or hold to its word, much less treat other nations with a modicum of decency or honor. The United States has become a rogue state.

Trump repeatedly implied that Iran is continuing to develop nuclear weapons. This is not the case. The point of the Iran deal was to limit that country's nuclear program to non-military uses, and in return relax some of the sanctions that have been strangling Iran's economy. The official International Atomic Energy Agency inspectors and U.S. intelligence agencies have both repeatedly confirmed that Iran is holding its end of the bargain, and not pursuing a nuclear weapons program.

In return, America had already gone back on its word in part, by imposing more sanctions for reasons having nothing to do with the deal. Now Trump is unilaterally breaking the deal for reasons entirely based on domestic politics and the neuroses of his own befogged brain. Iran is a handy bogeyman for the profoundly Islamophobic extreme right and the deal was the biggest remaining diplomatic accomplishment of President Obama. So that is that.

Moreover, France, Germany, Russia, the U.K., and China are all still parties to the deal, and all of them still believe the agreement is holding. There is virtually no chance that diplomatic system will be able to be reimposed. Indeed, many Iranian elites have argued Iran should continue to stick to the deal despite the U.S. betrayal, if European powers will continue to uphold it.

In administrations past, the grotesque irresponsibility of such a move would have prevented even very stupid presidents from making it. Neoconservative warmongers constantly shout about how it's important to Send a Message by Demonstrating Strength (that is, by killing thousands upon thousands of people halfway around the globe for no particular reason), but this act sends a far worse and far more comprehensible message: that the United States' word is worthless. Why would any country sign any deal or treaty of any kind with America, if it might be casually discarded at any time for deeply petty or actively evil reasons?

This is a mistake so idiotic it would not even occur to your average middle school Model U.N. participant. But that's the modern Republican Party for you.

Trump is scheduled to try to negotiate a deal with North Korea soon which of necessity would look very much like the Iran deal. In fact, in addition to his Iran deal announcement, the president said Tuesday that he had dispatched Secretary of State Mike Pompeo to Pyongyang for a series of meetings with North Korean officials. But the only reason such a thing could possibly succeed now is if the Koreas and China have sufficient confidence in their own arrangements so as to make U.S. participation basically unimportant.

And perhaps that will be for the best. In retrospect, the Iran deal will probably be seen as the last gasp of the postwar America-dominated international order. That system — underpinned by a largely America-funded and -dominated United Nations, International Monetary Fund, World Bank, NATO, and so on — can fairly be seen as a U.S. empire, though it should be noted that the countries of Western Europe, Japan, South Korea, Australia, and New Zealand all made out fairly well.

It has long been obvious that with China's spectacular growth and vast population, the unipolar post-Cold War world was going to become a bipolar one — or perhaps tripolar, if India can become rich before it is strangled by climate change. Power is going to shift to where the bulk of the world population is: southern and eastern Asia.

Scholars have been pondering for years how America might deal with the presence of a peer nation for the first time since 1991 — or even an actual superior power for the first time since the early 20th century. Could China's authoritarian state-capitalist system be integrated into a global order nominally based on liberal capitalism? Would India provide a democratic counterweight?

It turns out that America is actually going to drive itself from the international scene through a bevy of self-inflicted wounds and slapstick pratfalls that must be equal parts hilarious and terrifying to witness from the outside. We can't be trusted to not start pointless, criminal wars of aggression that cost trillions and drastically harm our national security. We can't be trusted to not elect as president an utter buffoon with literally zero experience who neither understands nor cares to understand the delicate international diplomatic system. Our legislative branch can't be trusted to act rationally when that buffoon predictably does idiotic, dangerous, deeply humiliating things that directly undermine the national interest. And our ancient, malfunctioning constitutional structure provides no recourse to the 63 percent of the population that wants to stay in the deal.

Make no mistake, America can still inflict horrendous damage before it becomes too feeble — or its military too corrupt and broken — to attack anyone else. If the rest of the international community has any sense, they will start constructing an international framework to fence in the U.S. — before it's too late.