Today, Japan marked the 70th anniversary of its pacifist Constitution, which specifically renounces war as a tool to resolve disputes. But the moment came with a couple of large asterisks.

Japan has a military – it’s known as the Self-Defense Forces. On Monday, one of its warships escorted a US Navy supply ship toward the Korean Peninsula. There, it will join the USS Carl Vinson – and two Japanese destroyers – in military exercises.

That relates to the second asterisk: Also today, Prime Minister Shinzo Abe unveiled his plan to revise that pacifist Constitution. He wants, he says, to clarify the role of the Self-Defense Forces.

Few would argue that the security environment Japan confronts has changed dramatically – most recently with Kim Jong-un’s intensified nuclear threats. But its World War II military aggression still hangs over Asia. That means Japan has a more fundamental challenge: addressing the fears of those who felt its sting. Mr. Abe said today that Japan “must hold fast to the idea of pacifism.” That outlook is deeply rooted in Japanese society, even though a slight majority of Japanese support revision. His acknowledgement may be a calming first step.