It seems all but official. Newspapers are reporting that according to Japanese government sources, the United States government has come to decision to retire the nuclear-armed Tomahawk cruise missile (TLAM/N). The retirement of these cruise missiles essentially closes the door on the deployment of U.S. tactical nuclear weapons in the East Asia theater.
In December, Dr. Jeffrey Lewis at published a vital research note on a dangerous fundamental flaw in the TLAM\N that would seemingly make it unusable against its most likely targets in North Korea. Also in December, Foreign Minister Okada Katsuya sent letters to the U.S. secretaries of state and defense disavowing a Japanese government intent to offer advice to the U.S. government on the desirability of particular U.S. nuclear weapons systems.
Today's article on the purported decision in The Asahi Shimbun makes note of the fundamental logical inconsistency (also noted by The Japan Times) regarding Japan's advocating the redeployment of these short-range missiles on U.S. attack submarines. Where would these vessels stop and where would they sail if their presence in Japanese waters or arrival in a Japanese port violates the "no-introduction" pledge of the Three Non-Nuclear Principles? Would a submarine positioning itself to defend Japan with TLAM\Ns have to start its voyage in Guam, then enter the Sea of Japan on the South Korean side of the Tsushima Straits in order to avoid triggering a violation of the pledge? Furthermore, how could a government that made a campaign promise to expose the existence of heretofore denied secret agreements on the introduction of nuclear weapons into Japan during military contingencies then turn around and adopt a Don't Ask/Don't Tell policy for U.S. submarines possibly carrying TLAM/Ns?
Unanswered at the end of this drama is the question of who ordered Japan's diplomats to lobby the Congressional Commission on the Strategic Posture of the United States (the Perry Commission) to suggest in its report that the U.S. retain the TLAM/N...and under what conception of Japan's stance on nuclear weapons was such lobbying justified. "Go and sin no more," seems to be Okada's view toward his bureaucrat subordinates...and his decision to not look into this matter further seems a wise choice.