President Donald Trump said on Wednesday the Secret Service was investigating what he described as “sabotage” at the United Nations, alleging that an escalator malfunction, a teleprompter failure and sound problems disrupted his appearance at the world body a day earlier.

Trump, in a post on his Truth Social platform, said an escalator carrying him and his wife Melania “came to a screeching halt” on the way to the main floor, nearly causing them to fall. He called for the arrest of whoever was responsible.

He also said his teleprompter went dark at the start of his speech and that world leaders in the hall could not hear him because the sound system had failed.

“Not one, not two, but three very sinister events!” Trump wrote.

U.N. officials have said the escalator’s built-in safety mechanism had been triggered and that the teleprompter was operated by the White House, not the organization.

Calling the series of events “triple sabotage,” Trump said he had asked the U.N. to preserve security camera footage and demanded an investigation. He said the Secret Service was looking into the matter.

U.N. officials did not immediately respond to a request for a comment on Trump’s call for an investigation.

U.N. spokesperson Stéphane Dujarric said on Monday that a readout of the escalator’s central processing unit indicated it “had stopped after a built-in safety mechanism on the comb step was triggered at the top of the escalator.”

Dujarric said Trump’s videographer had been traveling backward up the escalator to capture his arrival with the first lady. “The videographer may have inadvertently triggered the safety function,” he said.

A U.N. official told Reuters on Tuesday that the White House had operated its own teleprompter.

Responding to the allegation that delegates had not been able to hear Trump, the official said the sound system was designed to allow people at their seats to hear speeches being translated into six different languages through earpieces.

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(Reporting By Jarrett Renshaw, additional reporting by Michelle Nichols, editing by Ross Colvin and Deepa Babington)