Here's what would happen if a nuclear bomb was dropped on Portsmouth in event of WW3

The US President also revealed his intentions to develop new ballistic missiles '“ raising fears of a new arms race and even World War 3. 

The landmark IRNF treaty, signed by America and Russia in 1987, eliminated all nuclear and conventional missiles, as well as their launchers, with ranges of 500'“1,000 kilometres (310'“620 mi) (short-range) and 1,000'“5,500 km (620'“3,420 mi). 

Earlier this year The News revealed that Portsmouth was one of the key Russian targets during the cold war '“ with Portsmouth Naval Base topping the list of strategic targets. 

While the likelihood of WW3 and a nuclear holocaust remain extremely slim, could Portsmouth still be a Russian target in the event of a new global conflict? 

The website NUKEMAP estimates what would happen if a nuke was dropped on Portsmouth '“ it has been created by nuclear weapon expert and science historian Alex Wellerstein. 

NUKEMAP calculates the predicted number of fatalities and injuries that would be caused - based on the size of a the bomb dropped on the city '“ for this story we have selected the option of the bomb exploding as an airblast. 

So if the '˜Little Boy' 15 kiloton bomb, which was dropped by the US on the Japanese city of Hiroshima in WW2, fell on the Fratton area of the city 54,800 people would be killed and 61,490 would be injured. 

The fireball would have a radius of 180m, the air blast radius - which would severely damage buildings '“ would be 340m and the radiation radius '“ where death rates would be between 50% and 90% - would be 1.2km. 

However the '˜Little Boy' hasn't been used since WW2, so if a 350kt W-78 nuke '“ currently the largest option on NUKEMAP '“ it would be much more devastating. 

With 129,710 being killed, if the bomb was dropped on Fratton, and an estimated 191,590 more being injured. 

The fireball radius would be 0.63km, the air blast radius - which would severely damage buildings '“ would be 4.95km, the thermal radiation radius '“ causing third degree burns, scaring, disablement, and can require amputation - would be 7.67km. 

All of this is hypothetical and the risk of a nuclear bomb falling on Portsmouth is extremely low.