Ukrainian forces are retaking the territories occupied by Russia one by one recently.
As the war situation became unfavorable to Russia, there are reports that President Putin is trying to press the West with nuclear weapons.
Kwak Sang-eun is a correspondent in Paris.
Russian military train was caught moving from central Russia toward the front of Ukraine.
The Times reported that the train was linked to the 12th General Bureau, which is in charge of the maintenance, transport and management of nuclear weapons in the Russian Ministry of Defense.
A Russian submarine carrying the nuclear torpedo Poseidon, called the 'weapon of the end of the world', has also been found to have set sail for the Arctic Ocean.
There are speculations that a nuclear test is imminent in the Kara Sea region of Russia's Arctic Ocean.
As Russian President Putin, who has repeatedly threatened nuclear weapons, is on the defensive in the war, concerns are growing that he may be launching a full-fledged nuclear force demonstration.
An ex-Russian oil tycoon who was expelled by Putin and is in exile in the UK has mentioned the possibility that Putin's threat will not stop with words.
[Mikhail Khodorkovsky / Former Russian oil tycoon: If the war does not win even with the mobilization of the military, (President Putin) must also consider using tactical nuclear weapons.]
CNN broadcast Reportedly, it is considering countermeasures for a wide range of scenarios, including the possibility of use.