President Joe Biden has been accused of "falling asleep" during opening sessions at the Cop26 climate conference in Glasgow, Scotland.
At 78, Biden is the oldest person to serve as president of the United States, and his health and mental fitness for the job have been a subject of speculation by critics, including former president Donald Trump and his supporters.
Twitter users slammed Biden after a video clip first shared by a reporter for The Washington Post seemingly showed the US president listening with his eyes closed, per Forbes.
He is then seen listening to a speaker remarking that the world leaders assembled for the conference have the "power to make decisions and reach agreements which will affect the lives of generations to come" when he appeared to close his eyes for roughly 20 seconds.
An aide then approached and began to whisper to Biden, who turned his head to listen briefly before he began listening to the speech once more.
The moment came more than an hour into a series of opening speeches at the event, with Biden joining a standing ovation for an address from Sir David Attenborough a few minutes beforehand.
It was an early start for Biden, who stayed overnight at the US ambassador’s residence in Rome following the G20 summit, before making his way to Glasgow onboard Air Force One.
The clip has led to mockery from critics of the US leader, who was nicknamed "sleepy Joe" by Trump during the 2020 US presidential election.
Meghan McCain wrote: "An interesting conversation to be had while we debate if Biden fell asleep at a conference - why is this age rage of 75-80 something people so averse to retirement, conceding power, jobs? While they pull our generation into crisis & despair for their egos and fear of mortality..."
Columnist Benny Johnson added: "Looks like BIDEN JUST FELL ASLEEP, head-jerking during the OPENING SPEECHES at COP26 Watch as a staffer has to come wake him up to then clap for a speech he snoozed through SO HUMILIATING."
While another critic wrote: "What a global embarrassment he is.. Biden appears to fall asleep during COP26 opening speeches."
"Holy s**t it looks like Biden fell asleep at the climate thing and an aide had to hustle over to wake him up Anyone see this????" a fourth added.
In his own address to the conference later on Monday, November 1, Biden said: "We can keep the goal of limiting global warming to 1.5C within our reach if we come together, if we commit to doing the part of each of our nations with determination and with ambition.
"Climate change is already ravaging the world. It’s costing our nations trillions of dollars. None of us can escape the worst that’s yet to come if we fail to seize this moment. We’re standing at an inflection point in world history."