Vladimir Putin could launch a "tactical" nuclear strike but it would mean the end of Russian civilisation, a historian has warned.
It is estimated that the Russian president has 2,000 tactical nuclear weapons and some have the power to kill 10s of thousands of people with one strike.
Putin's troops have been met with fierce resistance from Ukrainians and have suffered severe casualties on the battlefield - including forces, high-ranking military generals and top-notch equipment.
