Photo/IllutrationPrime Minister Shinzo Abe and U.S. President Donald Trump after their joint news conference in Washington on Feb. 10 (Takeshi Iwashita)

The latest joint statement by Japanese and U.S. leaders mentions nuclear weapons as a U.S. option to defend Japan for the first time since 1975, reflecting growing concerns about North Korea.

The statement released Feb. 10 by Prime Minister Shinzo Abe and U.S. President Donald Trump after their summit talks in Washington states: “The U.S. commitment to defend Japan through the full range of U.S. military capabilities, both nuclear and conventional, is unwavering."

Tokyo and Washington agreed they had to reaffirm the "nuclear deterrence" due to the threat posed by North Korea's repeated missile and nuclear tests, said Takeo Mori at a meeting of the ruling Liberal Democratic Party on Feb. 14.

Mori, director-general of the Foreign Ministry's North American Affairs Bureau, said it was only the second time for Japanese and U.S. leaders to release a document that uses the word “nuclear” in terms of the U.S. defense of Japan.

The previous one, in August 1975 by Prime Minister Takeo Miki and U.S. President Gerald Ford, stated: "(The) United States would continue to abide by its defense commitment to Japan under the Treaty of Mutual Cooperation and Security in the event of armed attack against Japan, whether by nuclear or conventional forces.”

That is believed to be the first document to unequivocally announce that Japan was covered by the U.S. “nuclear umbrella.”

The nuclear option has never been specified in a joint statement by Japanese and U.S. leaders since then because it was considered obvious that the United States would use all means to defend Japan.

The two countries have avoided referring to nuclear deterrence out of consideration for the feelings of people in Japan, many of whom harbor intense feelings about the 1945 atomic bombings of Hiroshima and Nagasaki, according to a former senior Foreign Ministry official.

(This article was written by Kayoko Geji and Hajimu Takeda.)