During Wednesday’s commemorations in Hiroshima, Japan, marking 80 years since the first atomic bomb strike in history, the city’s mayor Kazumi Matsui called on the Japanese government to sign the Treaty on the Prohibition of Nuclear Weapons. Tokyo has previously refused, saying it would send the “wrong message.” Even as it officially opposes nuclear weapons, Japan depends on nuclear deterrence, as afforded by the United States. Host Carolyn Beeler learned more about the country’s tricky balancing act on nuclear policies from Masako Toki. She’s with the James Martin Center for Nonproliferation Studies at the Middlebury Institute in Monterrey, California.