Myanmar's junta is already facing an "existential threat," but the world could help end its "nightmare" rule with coordinated sanctions, the U.N. special rapporteur on the country said Wednesday.

Mass casualties among junta forces, as well as defections, surrenders, and recruitment challenges have led to dwindling troop numbers, posing "an existential threat for the Myanmar military," said Tom Andrews.

"Those who have bet on the junta to restore order and stability in Myanmar have made a losing bet," he said.