They will visit Hiroshima Peace Park and conclude their gathering with a “Hiroshima Declaration” that will likely express hope for a world without nuclear weapons.

The future of such weapons and how to reduce them is shaping discussions in Tokyo and Hiroshima this year, following the nuclear security summit held in Washington on March 31 and April 1 and the upcoming G-7 Ise-Shima summit at the end of next month.

But even as Japan seeks to play a larger role in international nonproliferation efforts, past personal statements by Prime Minister Shinzo Abe, his allies, and, more recently, official government replies about nuclear weapons for Japan, raise questions about how politically credible any leadership in that role might be.

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