Comments by US President Donald Trump and a "darkening global security landscape" have made the world less safe, the Bulletin of the Atomic Scientists warned Thursday, moving its symbolic "Doomsday Clock" 30 seconds closer to midnight.
The clock is a metaphor for how close humanity is to destroying the planet and itself. It was last shifted in 2015, from five to three minutes to midnight.
It is now set at two and a half minutes to the extinction of humanity.
The decision to move the clock or not is made each year by a group of scientists and intellectuals, who currently include 15 Nobel prize winners.
"A rise in strident nationalism worldwide, President Donald Trump's comments on nuclear arms and climate issues, a darkening global security landscape that is coloured by increasingly sophisticated technology, and a growing disregard for scientific expertise," prompted the group on Thursday to move the minute hand 30 seconds closer to catastrophe.
"Never before has the Bulletin decided to advance the clock largely because of the statements of a single person," two scientists at the Bulletin, Lawrence Krauss and David Titley, said in an opinion piece published by The New York Times.
"But when that person is the new president of the United States, his words matter."
The Bulletin of the Atomic Scientists created the "Doomsday Clock" in 1947. Since then it has ranged from two minutes to midnight in 1953 after the hydrogen bomb was tested to 17 minutes before midnight in 1991 as communism began to unravel.