Keir Starmer, the newly elected prime minister, appeared to call Mr. Musk out. “To large social media companies and those who run them,” Mr. Starmer said at the time, “violent disorder, clearly whipped up online, that is also a crime.” Mr. Musk took the bait. He branded the remarks “insane” and spent the following weeks spreading the nickname “two-tier Keir” — a reference to the conspiracy theory that there is a “two-tier” system of policing in Britain, in which white people are punished more harshly than minority groups. He even shared (then deleted) a fake headline that claimed Mr. Starmer’s government was building “emergency detainment camps” for the rioters.

Since the summer, Mr. Musk’s comments about the country have become even more extreme. In September, he falsely accused the Starmer government of “releasing convicted pedophiles from prison in order to put people in prison for Facebook posts.” He has repeatedly championed the cause of Tommy Robinson, a far-right, anti-Islam British activist with a slew of criminal convictions currently in jail for repeatedly breaking an injunction. During a posting spree at the start of January, Mr. Musk called for a government minister to be imprisoned, for new elections to oust the prime minister and for Mr. Starmer to be charged for complicity in the “rape of Britain.”

All of this could be an attempt to distract from X’s role in the summer riots, for which lawmakers plan to summon him to testify to Britain’s Parliament. Some have wondered whether it might be down to his sleeping habits: Data compiled by The Economist on his posting times suggests he sleeps for only a few hours a night — meaning he is awake and online when the British news cycle begins. The most compelling explanation, though, is ideological.

In his posts, Mr. Musk focuses relentlessly on immigration, free speech, regulation and crime. On these issues, Britain’s center-left government appears to be anathema. And not only for him. For those around Donald Trump, Britain is a “country that is being destroyed,” as Kari Lake put it, or the first “truly Islamist country” with nuclear weapons, as JD Vance bizarrely claimed. American conservatives have often used this type of apocalyptic language about countries such as Venezuela. But Mr. Musk is now spearheading an attempt to turn Britain — one of America’s closest allies — into their new adversary.

Much of the material for this narrative, oddly, comes from Britain itself. Since the Conservatives were defeated last summer, disaffected right-wingers have sought solace in trash-talking their country to an American audience. The former home secretary, Suella Braverman, insists that Britain is beset by a “lunatic woke virus” — language favored by the likes of Ron DeSantis. Liz Truss, the former prime minister who has appeared at the Republican National Congress, on Fox News and alongside Steve Bannon, rails against the shadowy “deep state” forces that supposedly brought her 49-day tenure to an end.