Vladimir Putin will only resort to using nuclear weapons if Russia faces an "existential threat" - possibly with NATO troops bearing down on Moscow - a former foreign minister has claimed.
Andrei Kozyrev, who served under Putin's predecessor Boris Yeltsin in the 1990s, played down fears that the irrational Russian president may unleash the country's nuclear arsenal any day now.
International experts are split on how likely this is, with his invasion of Ukraine not going to plan.
