Japanese Chief Cabinet Secretary Matsuno said on Monday that the government has decided to ban export of chemical weapons related goods to Russia as an additional sanction on Moscow over its invasion of Ukraine. Matsuno said Japan was deeply concerned about the possibility of use of nuclear weapons.

Japan also added 21 Russian organizations, including science labs as the target of existing export bans, according to a government statement released after Monday’s cabinet meeting, which formally approved the new sanction measures.

“As the world’s only country to have suffered nuclear attacks, we strongly demand that the threat or use of nuclear weapons by Russia should never happen,” Matsuno said during a regular news conference.

“Japan is deeply concerned about the possibility of nuclear weapons used during Russia’s invasion of Ukraine,” Matsuno also said at the media briefing, adding Japan will continue to work with the international society in supporting Ukraine and sanctioning Russia.

Matsuno also responded to a question about U.S. National Security Advisor Sullivan’s comments on Sunday that the United States would act decisively in case of a Russian nuclear attack on Ukraine.

Asked if Japan approves of the possible use of nuclear weapons by the United States against Russia, Matsuno refused to comment, saying that it was a hypothetical question.