Yoon Suk-yeol on Sunday raised the possibility that Seoul and Washington could include Japan in nuclear planning efforts in order to strengthen deterrence against North Korea, only for his office to quickly walk back his comments.

“The Washington Declaration is an agreement between South Korea and the United States. But this does not rule out Japan’s participation,” the South Korean president said in a press conference following his summit with Japanese Prime Minister Fumio Kishida in Seoul, according to a presidential office press release.

The U.S. and South Korea announced the declaration in late April during Yoon’s state visit to