Keir Starmer has said standing up to Russia is "about our way of life" as he called on Vladimir Putin to back down on his nuclear war threats. The PM responded after Russian tyrant Vladimir Putin approved a new nuclear doctrine as fears of a third worldwide conflict escalate. Asked how worried he is, he said Putin cannot be allowed to win.

Russian President Vladimir Putin signed a revised nuclear doctrine on Tuesday to effectively lower his country's threshold for using nuclear weapons. Why it matters: The new doctrine suggests Russia could use nuclear weapons to respond to attacks by Ukraine carried out with American support.

Russian President Vladimir Putin appeared to threaten to use nuclear weapons if Ukraine fired American-made missiles into Russia.

The timing of the new doctrine is crucial. It follows President Joe Biden’s decision to allow Ukraine to use US-supplied ATACMS missiles to strike targets within Russia, escalating concerns in Moscow about the West’s growing involvement in the conflict.

Putin ramps up nuclear attack threat after Biden backs Ukraine firing US-supplied missiles into Russia - China is believed to have warned Moscow against a nuclear strike

Russian President Vladimir Putin approved updated principles of Russia's nuclear deterrence policy, according to a presidential decree published on a government website on Nov. 19. The revised doctrine outlines scenarios that could justify a nuclear strike.

Russia has warned that the Biden administration's approval for Ukraine to use long-range US missiles (ATACMS) represents a significant escalation in the conflict. Kremlin spokesperson Dmitry Peskov called it a new stage of US involvement.