The last time a U.S. president visited Hiroshima, atomic bomb survivor Shigeaki Mori was filled with hope for a future without nuclear weapons. Seven years later, he's more skeptical.

As leaders of the Group of Seven nations gather in the Japanese city this week for a summit, Prime Minister Fumio Kishida wants a pledge on nuclear disarmament.

Kishida, who represents Hiroshima, said he chose it for the summit to focus attention on nuclear weapons. But the venue has also highlighted a significant shift in global security since 2016, when Barack Obama became the first incumbent U.S. president to visit.