Ukrainian President Volodymyr Zelensky told CNN Friday that "all of the countries of the world" should be prepared for the possibility that Russian President Vladimir Putin could use tactical nuclear weapons in his war on Ukraine.

Zelensky told CNN's Jake Tapper in an exclusive interview from the office of the president in Kyiv on Friday that Putin could turn to either nuclear or chemical weapons because he does not value the lives of the people of Ukraine.

"Not only me — all of the world, all of the countries have to be worried because it can be not real information, but it can be truth," Zelensky said, speaking in English.
"Chemical weapons, they should do it, they could do it, for them the life of the people, nothing. That's why," Zelensky said. "We should think not be afraid, not be afraid but be ready. But that is not a question for Ukraine, not only for Ukraine but for all the world, I think."

Zelensky has remained in Ukraine throughout the course of the 50-day war with Russia, as Ukraine's forces have resisted the Kremlin's attempts to seize Kyiv and forced Russia to refocus its war efforts on the eastern and southern regions of the country, where Ukraine is anticipating a significant escalation in fighting in the days to come.

One of Russia's most important naval warships sunk in the Black Sea this week, which Ukraine said was the result of a missile strike, while Russia claimed it was due to a fire from the detonation of ammunition.

At the same time, Russia is firing cruise missiles into the outskirts of Kyiv and still maintains the ability to target Ukraine's capital with long-range weaponry.

US officials have warned about the possibility that Putin, if backed into a corner, could turn to the use of tactical nuclear weapons in Ukraine. CIA Director Bill Burns said Thursday that the CIA watches "very intently" over the possibility, while emphasizing that the US has not yet seen any signs that Russia is preparing to take such a step.

"Given the potential desperation of President Putin and the Russian leadership, given the setbacks that they've faced so far militarily, none of us can take lightly the threat posed by a potential resort to tactical nuclear weapons or low yield nuclear weapons," he said in public remarks at Georgia Tech, CNN reports.