MOSCOW

Russian Security Council Deputy Chairman Dmitry Medvedev said on Tuesday Moscow may use nuclear weapons first in case of any aggression against it or its allies.

Opponents should not underestimate Russia's determination, said Medvedev, who also served as the Russian president between 2008 and 2012, during an educational marathon in Moscow called "Knowledge," a platform for open discussions between young people and government representatives.

When asked about climate change, Medvedev responded, "Do you really care about the climate to such an extent? In my opinion, this is nothing compared to the prospect of being at the epicenter of an explosion with a temperature of 5,000 Kelvin (scale). Is there such a prospect today? (Unfortunately,) yes. And it is growing every day for well-known reasons," he said.

The modern world is “sick,” and a world war is possible, but it can still be avoided, he believed.