But conspiracy theory website DEFCON warning system claims the threat has been upgraded to level 3, meaning the US Air Force is ready to mobilise in just 15 minutes.
The website, which bases its warning on “current affairs”, writes: “Tensions between Russia and the United States have reached levels beyond the cold war in the recent week.
“The situation between Russia and the United States is extremely fluid at the moment. In all likelihood as dynamic as at times during the Cuban Missile Crisis of 1962.
“At this time, the DEFCON Warning System feels that an increase to DEFCON 3 would be a prudent move.”