Following a Japanese atomic bomb survivors group’s historic Nobel Peace Prize win Fridaythe country’s stance on nuclear disarmament has once again been put under the spotlight.

Prime Minister Shigeru Ishiba, a long-time advocate of nuclear deterrence through the sharing of nuclear weapons, said Sunday that his government will “seriously consider” participating as an observer in a conference of signatories to a United Nations treaty that bans the weapons.

Adopted by the UN in 2017, the Treaty on the Prohibition of Nuclear Weapons (TPNW) bans the development, testing, production, acquisition, possession, stockpiling and use of nuclear weapons, as well as the threat to use them. It has since been ratified by dozens of countries around the world, but none of the declared nuclear weapons states — namely the United States, United Kingdom, France, China and Russia — has followed suit.