Russia Ukraine War: What is Putin's 'nuclear plan'?

UN Secretary General Antonio Guterres on Monday said that Russia putting nuclear forces on high alert is a "chilling development" amid the Russian invasion of Ukraine.

"Nothing can justify the use of nuclear weapons," he said at the emergency session of the General Assembly on Ukraine.

"Yesterday, Russian nuclear forces were put on high alert. This is a chilling development. The mere idea of a nuclear conflict is simply inconceivable."