A chilling new graphic has revealed the devastating reach of an “atmospheric burst” that could be released from a hypothetical nuclear explosion over the Pacific Ocean.

The simulation of a “radio-isotope cloud” spreading for two weeks across the ocean towards Asia and the US was released on the Twitter account of Lassina Zerbo, the head of the Comprehensive Nuclear Test Ban Treaty Organisation, a group tasked with monitoring weapons tests.

It offers no supporting data, including the yield or altitude of the theoretical bomb, or the threat that the cloud would pose to human health.