Japan will not file a complaint against the U.S. government for conducting two subcritical nuclear experiments, last Dec. 1 and Feb. 2, Deputy Chief Cabinet Secretary Tetsuro Fukuyama said Wednesday.
The U.S. National Nuclear Security Administration reported in June that the two tests had been held at a Nevada underground test site, Fukuyama said.
In subcritical tests, plutonium is bombarded with conventional explosives, but they do not involve a nuclear bomb explosion.
However, the government will not lodge a protest with the U.S. as subcritical nuclear tests are not banned under the Comprehensive Nuclear Test Ban Treaty.
"The Japanese government understands that the U.S. conducts subcritical experiments to ensure the safety and effectiveness of its nuclear weapon storage without holding full-scale nuclear explosions," Fukuyama said.
Subcritical tests have been conducted three times under the leadership of President Barack Obama, who won the Nobel Peace Prize in 2009 largely based on his vision of creating "a world without nuclear weapons."