In a diplomatic response to the agreement,
China's President Xi Jinping proposed a Southeast Asia nuclear weapon-free treaty.
Mr Xi announced his plan during a virtual summit of leaders from the Association of Southeast Asian Nations (ASEAN).
"China supports ASEAN's efforts to build a nuclear weapon-free zone, and is prepared to sign the Protocol to the Treaty on the Southeast Asia Nuclear Weapon-Free Zone as early as possible," Mr Xi Jinping said.
The Southeast Asia Nuclear Weapon-Free Zone is an agreement signed in 1995 between 10 Southeast Asian member-states.