Osaka Mayor Hirofumi Yoshimura will end Osaka's six-decade sister city relationship with San Francisco after the mayor of the U.S. city, Edwin Lee, signed a resolution Wednesday that designates as city property a memorial to "comfort women" — women and girls who were forced to work in Japanese military brothels before and during World War II.

"The sister city relationship of trust is gone. I'll undertake measures to dissolve it," Yoshimura said Thursday evening.

The memorial, dedicated in September to the so-called comfort women, has been the subject of long-standing tensions between memorial supporters and the Osaka mayor. The Japanese government has also protested the memorial. Chief Cabinet Secretary Yoshihide Suga said it was in conflict with Japan's position on the comfort women issue.