The Doomsday Clock was moved one second forward to 89 seconds to midnight. The latest move is the closest ever.
The Bulletin of the Atomic Scientists (BAS) said that the main factors of the move such as nuclear threats, potential misuse of advances in biology, artificial intelligence, and climate change.
Daniel Holz, chair of the Bulletin's Science and Security Board, said the latest move was "a warning to all world leaders".
The clock was originally placed at seven minutes to midnight in 1947. Last year, it was left unchanged at 90 seconds.
In the statement, the BAS said: "In setting the clock one second closer to midnight, we send a stark signal.
"Because the world is already perilously close to the precipice, a move of even a single second should be taken as an indication of extreme danger and an unmistakable warning that every second of delay in reversing course increases the probability of global disaster."
"Conflict in the Middle East threatens to spiral out of control into a wider war without warning," the statement said.