On Friday North Korean dictator Kim Jong Un praised his country’s recent hydrogen bomb test and satellite launch as “unprecedented” achievements that will “bring the final victory of the revolution.” Such rhetoric is nothing new, but North Korea’s nuclear-weapons program and a growing sense that security arrangements with the U.S. aren’t sufficient has eroded the Japanese taboo against nuclear weapons. On April 1, Prime Minister Shinzo Abe’s cabinet announced that Japan’s constitution did not ban his country from having or using nuclear arms.

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