US President Joe Biden has warned that the risk of a nuclear «Armageddon» is at its highest level for 60 years.
Mr Biden said that Russian President Vladimir Putin was «not joking» when he warned that Moscow would use «all means we have» to defend Russian territory. Mr Putin has also said that the US created a «precedent» by using nuclear weapons in World War Two.
But analysts suggest Mr Putin’s words should probably be interpreted as a warning to other countries not to escalate their involvement in Ukraine, rather than signalling any desire to use nuclear weapons.
Nuclear weapons have existed for almost 80 years and many countries see them as a deterrent that continues to guarantee their national security.
All figures for nuclear weapons are estimates but, according to the Federation of American Scientists, Russia has 5,977 nuclear warheads – the devices that trigger a nuclear explosion – though this includes about 1,500 that are retired and set to to be dismantled.
Of the remaining 4,500 or so, most are considered strategic nuclear weapons – ballistic missiles, or rockets, which can be targeted over long distances. These are the weapons usually associated with nuclear war.