Joe Biden's staff cut him off as he was mid-way through a speech in Hanoi, Vietnam, on Monday (11 September).
Many in the audience were left puzzled as the US president trailed off during a press conference.
Mr Biden was speaking at the end of a historic visit in which he highlighted new business deals and partnerships between the former enemies.
"And look, nobody likes having celebrated international meetings if you don't know what you want at the meeting... I’m going to go to bed,” Mr Biden said, before he was cut off by White House staff.
