Japanese Prime Minister Fumio Kishida on Saturday warned that the threat of Russia using nuclear weapons was looking “increasingly real” as he hosted US envoy Rahm Emanuel at Hiroshima, the site of the first nuclear attack in human history.

“When the possible use of nuclear weapons by Russia is increasingly real, I believe Ambassador Emanuel’s visit to Hiroshima and his experience of seeing the nuclear reality will become a strong message to the international society,” Kishida was quoted as saying by Japanese media outlet NHK.

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Kishida’s comments reflect growing international concern about the possible use of nuclear weapons by Russia. It also reflects Tokyo’s anti-nuclear stance: Japan, being the only country to have suffered a nuclear attack, has long spoken out against nuclear weapons.

That being said, Russian President Vladimir Putin has not directly threatened to use nuclear weapons yet, despite warning the international community of “consequences that you have never encountered in your history” in retaliation to interference in Ukraine.

Kremlin spokesperson Dmitry Peskov, too, has ruled out the use of nuclear weapons in general, saying that Russia would only resort to the use of such weapons in the event of an existential threat to the country.

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“We have a concept of domestic security and it’s public, you can read all the reasons for nuclear arms to be used. So if it is an existential threat for our country, then it [the nuclear arsenal] can be used in accordance with our concept,” Peskov had told CNN a few days back, in an attempt to alleviate Western fears of a nuclear attack on Ukraine.

While Russia has resorted to the use of banned or controversial weapons such as thermobaric missiles, cluster munitions, and white phosphorus, there is no evidence to suggest that Moscow has plans of using its nuclear arsenal.