North Korea conducted its fifth and most powerful nuclear test to date around 9:30 a.m. Friday, prompting Tokyo to immediately file a protest amid concerns over accelerating developments in the North's nuclear and ballistic missile technologies.
Tokyo lodged the protest through its embassy in Beijing, saying the test posed a "grave threat" to Japan, the region and international society, Chief Cabinet Secretary Yoshihide Suga told a news conference.
The United States and Japan are jointly urging the United Nations Security Council to convene an emergency meeting to condemn the North, Suga said.