A package bomb from Yemen removed from a cargo plane in the UK last month could have exploded over America’s East Coast.
The evidence questions previous theories that the device was meant to detonate in midair.
The Yemen device was disrupted by UK explosives officers when discovered and removed from the plane.
Had it been activated the original detonation time would have placed it over the populated US eastern seaboard.
The bomb was one of two dispatched from Yemen to fictitious addresses in Chicago with explosives packed into toner cartridges inside computer printers.
Since then cargo searches have been stepped up at Yemen airports as the hunt goes on for the al Qaeda branch thought responsible.
Governments and airlines around the world have been reviewing security since the foiled plot.