President Vladimir Putin has warned that he is ready to use nuclear weapons to defend Russia as it continues its aggression in Ukraine. He warned that he is not bluffing. The US and NATO are taking the situation seriously, says National Security Adviser Jake Sullivan.
"I have expressed myself clearly. President Biden and the administration have made it clear that there is a danger, given Putin's barefaced talk about the use of nuclear weapons. We have stated quite clearly what the consequences would be. We have communicated directly to the Russians".
The nuclear threat
According to Moscow's doctrine on the use of nuclear weapons, they are activated after an "aggression against the Russian Federation with conventional weapons, when the very existence of the state is threatened." The Kremlin's claims to 18% of Ukraine's territory have increased the risk, as Moscow may consider any attack on these territories as an attack on Russia itself.
Some British newspapers even suggest that Putin may be planning a nuclear test on the Ukrainian border. The Kremlin describes the reports as "nuclear rhetoric".
Nuclear arsenal
President Putin controls the world's largest nuclear arsenal, a new generation of hypersonic weapons and smaller tactical nuclear weapons. Russia has 5,977 nuclear warheads. The US has 5,428, China has 350, France has 290 and the UK has 225, according to the Federation of American Scientists.
Possible variants
Tactical nuclear weapons, built for battlefield use, have a destructive power many times smaller than strategic nuclear warheads. They can be launched from sea, air or land, although their effectiveness is a matter of debate among military experts.
But a nuclear weapon can be activated over a remote, uninhabited area or body of water like the Black Sea as a chilling demonstration of intent. Nuclear radiation would spread within a radius of about a kilometer.
The reaction of the West
"America is fully prepared to defend every inch of NATO territory. So, Mr. Putin, don't misunderstand what I'm saying. Every palm," said President Joe Biden.
NATO and the US have not given details on how they would respond to a Russian nuclear attack on Ukraine, but Washington says it has made Moscow aware of the "catastrophic consequences" that would follow.
Reactions could range from non-military, to a conventional military response by Washington or NATO, which would mean direct war with Moscow, or to a nuclear strike, which risks serious and immediate escalation.
"Our message is that any use of nuclear weapons is absolutely unacceptable and will completely change the nature of the conflict. Russia must know that a nuclear war cannot be won and should never be started," said NATO Secretary General Jens Stoltenberg.