North Korean leader Kim Jong Un and President Trump during a summit at Sentosa Island, Singapore, on Tuesday. (KCNA/EPA-EFE/Shutterstock)

When it comes to economics, history, foreign policy, health care, tax policy or any other field that it is important for a president to master, Donald Trump is an invincible ignoramus. But when it comes to salesmanship, Trump is an unparalleled genius — he is Dale Carnegie, P.T. Barnum and David Ogilvy rolled into one. His central insight is that in the post-truth, social media age, it is no longer necessary to achieve anything in order to claim a policy victory. You can just say over and over that you’ve accomplished your goals — and a lot of people will believe you even if it’s just not so.

This is why Trump says he is already building his border wall with Mexico even though Congress has not appropriated money for it and Mexico hasn’t volunteered to pay for it, as he once said it would. The president even tweeted photos of a wall being built. On closer examination, however, this turned out to be a section of fencing that was in the works before his election. But Trump no doubt assumes that his followers will never notice the fact checks from the “fake news media,” and, even if they do, will never believe them.

Trump applied the same method to the Iran nuclear deal. On June 7, he said that, as a result of his withdrawal from the accord, “Iran is acting a lot differently. They’re no longer looking so much to the Mediterranean. They’re no longer looking so much to what’s going on in Syria, what’s going on in Yemen and lots of other places. They’re a much different country over the last three months.” There is, in fact, zero evidence of any change in Iranian behavior. Tehran is threatening to ramp up nuclear production and carrying out war crimes in Syria, backing the Houthis in Yemen and engineering a political deal in Iraq to place its proxies in power. It is exactly the same country it was when Trump left the nuclear deal; if anything, it is now more dangerous.

All this was merely a prelude for Trump’s most audacious faux achievement yet. On Wednesday, he tweeted that “There is no longer a Nuclear Threat from North Korea.” In fact, North Korea’s nuclear capabilities are unaffected by Trump’s Singapore summit with Kim Jong Un. It hasn’t dismantled a single warhead or missile.

Kim’s only commitment was to “work towards the complete denuclearization of the Korean peninsula” — the same empty promise his country has made since 1992. Kim offered no nuclear inventory, no timetable and no verification procedures. All of the concessions were on Trump’s part: He agreed to end U.S.-South Korean military exercises (“war games”), and he elevated North Korea to equal status on the world stage (he even saluted a North Korean general!) while effectively neutering the sanctions regime. Why would any country enforce sanctions, after all, when the president has certified that North Korea no longer poses a threat?

In reality — remember that quaint concept? — this was the end of the nuclear threat in the same way that the 1938 Munich Agreement was “peace for our time.” As the Chosun Ilbo, South Korea’s leading newspaper, noted: “Kim Jong-un Got Everything He Wanted from Summit with Trump.” Trump, by contrast, did not get the “complete, verifiable, irreversible denuclearization” that he and his secretary of state, Mike Pompeo, had repeatedly promised.

But Sean Hannity, Trump’s de facto minister of propaganda, says Kim did agree to “complete, verifiable, irreversible denuclearization,” and that will be good enough for Trump’s base. His Fox “News” colleague Laura Ingraham is making fun of summit skeptics — who include pretty much all the experts on North Korea. “To listen to the @MSNBC panels and watch their faces this morning…,” she says, “it’s just like election night all over again. They can’t believe he pulled it off.”

Ingraham is echoing Trump — or is he echoing her? The president tweeted: “So funny to watch the Fake News, especially NBC and CNN. They are fighting hard to downplay the deal with North Korea. 500 days ago they would have ‘begged’ for this deal — looked like war would break out. Our Country’s biggest enemy is the Fake News so easily promulgated by fools!” So in the World According to Trump, North Korea is America’s friend (its leader has “a great personality,” “he’s a funny guy, he’s very smart, he’s a great negotiator,” “he loves his people,” and he no longer poses a nuclear threat) while the news media is the enemy.

This is deranged, but I bet if you poll Republicans in a week you will find that far more of them will identify “the Fake News” as America’s enemy than will name North Korea. A president who handed out worthless degrees from a fraudulent “university” is now minting made-up accomplishments — and the personality cult formerly known as the Republican Party is nodding along in zombie-like agreement.