The United Nations believes it has solved the mystery of why an escalator abruptly stopped shortly after the US President Donald Trump stepped onto it on Tuesday - his videographer may have accidentally triggered a safety mechanism. Trump jokingly complained about the incident during his speech to world leaders earlier on Tuesday after the teleprompter also didn't work. “These are the two things I got from the United Nations - a bad escalator and a bad teleprompter," he told the 193-member assembly, to some laughter. However, White House Press Secretary Karoline Leavitt wasn't so lighthearted about it. “If someone at the UN intentionally stopped the escalator as the President and First Lady were stepping on, they need to be fired...