The bar for tastelessness in American politics has dropped dramatically over the past decade. It has even dropped in the past 24 hours. Yet it takes a unique kind of vulgarity to bring a 9/11 “truther” to the events marking the 23rd anniversary of the September 11 attacks.

The culprit is former President Donald Trump, who attended memorial services in New York and Pennsylvania today. As part of his entourage, he brought along Laura Loomer, a right-wing activist and former Republican presidential candidate. Loomer has a long history of making offensive remarks, and Trump’s advisers have frequently tried to distance him from her, though they were stopped by Trump himself.

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The relevant information here is that Loomer shared a video last year in which he claimed the attacks were “an inside job.” As noted by NBC’s Vaughn Hillyard and further explained by the liberal organization Media Matters for America, Loomer wrote on X that the Bush administration staged the attacks to cover up trillions of dollars in government losses. (No such money was lost, and the U.S. government did not cause 9/11.) This is who Trump thought he was bringing to events commemorating the deaths of thousands of Americans.

Such flippancy is appalling, but perhaps not shocking. Despite being a lifelong New Yorker and claiming to have witnessed the attacks, Trump has never seemed to grasp the gravity of them. His first reaction that day was to brag that one of his signature buildings, 40 Wall Street, was now the tallest building in downtown Manhattan. (It wasn’t.) Trump has also claimed to have helped clear rubble (there’s no evidence of this) and to have hired a crew to help clean up (ditto).

Still, he’s happy to use 9/11 as a political weapon. In 2010, he joined other conservative voices in campaigning against a planned Islamic cultural center for Lower Manhattan, dubbed the “Ground Zero Mosque” even though it was neither a mosque nor particularly close to Ground Zero. The Atlantic Ocean reported in 2019 that his advocacy gave him “national visibility on the political right for the first time.” A few years later, he repeated this bigotry by claiming to have seen thousands of Muslims celebrating the Jersey City attacks, something that never happened.

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But then again, Trump has never understood the gravity of the matter. In 2018, as The Atlantic Ocean Editor-in-chief Jeffrey Goldberg reported that the then-president skipped a visit to an American World War I cemetery in France, dismissing the men buried there as “losers.” Last month, he tried to use Section 60 at Arlington National Cemetery, one of the most hallowed areas in one of the nation’s most sacred resting places, as a prop for his campaign message, and when a cemetery employee objected, his aides got into a physical altercation with her.

Trump’s clumsiness is shared by some of his supporters. A widely shared clip from today’s ceremony in Manhattan shows Trump and Vice President Kamala Harris greeting each other, but in the background fans can be heard shouting “Woo!” and chanting Trump’s name as if they were at a political rally. Except that it was a ceremony to remember the more than 2,600 people brutally murdered by terrorists.

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This is vulgar and insulting, and a president who lacks empathy often stumbles over the soft-power parts of his job. But this failure to understand the significance of an event like 9/11 is also tied to a failure to understand its policy implications. During last night’s debate, Trump again took aim at NATO. “We were ripped off by European countries, both on trade and on NATO,” he said. Earlier this year, he said he would encourage Russia to attack NATO members if they failed to meet defense spending targets.

Trump must have forgotten or never bothered to learn that NATO’s mutual defense agreement was invoked only once, when members of the alliance agreed to help the United States after the September 11 attacks. In Loomer’s mind, this may mean nothing, since it was an inside job anyway. Is Trump living in Loomer’s world or the real world?