John Kerry, the US secretary of state, had not even appeared at Hiroshima’s peace memorial before word leaked that US president Barack Obama could visit Hiroshima at the end of May following the G7 meeting in Shima, Japan.

The Obama administration, it’s safe to say, is in full legacy-building mode.

Last month, Myanmar’s government transitioned to a democratically elected government (and, yes, Kerry’s predecessor at State, Hillary Clinton, played a critical role in US support for Burmese democracy). There’s the landmark deal of the ‘P5 + 1’ countries with Iran to bring more transparency to its nuclear energy program and, possibly, its nuclear weapons ambitions. There’s the opening to Cuba after decades of isolation and resentment on both sides of the Straits of Florida, and Obama’s historic visit to Havana.

Kerry is now the highest-ranked US official to visit Hiroshima, but a presidential visit would be exponentially more important — and symbolic — for at least three reasons.

The first and most obvious is that the nuclear attacks on Hiroshima and Nagasaki, which marked their 70th anniversaries last August, have now been ‘internationalized.’

They are now symbols of the precipice of nuclear warfare and the threat of nuclear proliferation. To the extent that Hiroshima’s legacy calls out, ‘Never again,’ it’s a caution for the entire world, not just the United States or Japan. In that regard, Obama’s visit would accent eight years of mixed results on non-proliferation.

The second is that it could slow the efforts of prime minister Shinzō Abe (安倍 晋三) to weaken Article 9 of the Japanese constitution, which enshrines Japan as a pacifist country and limits Japan’s ability to form a conventional military. Since returning to power in 2013, Abe has tried to amend the constitution to permit a more muscular version of the country’s Self-Defense Forces. Though Abe is one of Japan’s most hawkish leaders, his concerns, in the face of rising Chinese hegemon and the constant threat of an erratic North Korea, aren’t ridiculous. Last week, for instance, Abe insisted that the Japanese constitution did not prevent the country from having a nuclear weapons program. US officials, who have worked closely with Japan for decades, worry that a more aggressive Japan could upset the security balance in east Asia (and the American ability to project its own power in the region). It’s notable that when Obama’s advisers first mooted a trip to Hiroshima at the beginning of his presidency, it was Japanese officials who nixed it.

Finally, it provide be a moment for Americans to reckon with the legacy of the Hiroshima and Nagasaki bombings. When Jon Stewart called the late president Harry S Truman a ‘war criminal’ for dropping the atomic bombs twice on Japan, he  backtracked quickly and apologized. The public backlash was staggering, considering it involved an event that few Americans today were even alive to remember.

It’s a sign that, despite the passage of decades, the American role in unleashing nuclear terror remained a sore subject. Obama’s Hiroshima visit, following so closely the 70th anniversary memorials last August, could provide the context for a less emotional assessment.

Generations of Americans have viewed Truman’s decision as a necessary, if painful, choice to end the war sooner with fewer casualties, both American and Japanese. Historians, however, point to the fact that American military leaders never considered dropping atomic bombs on Europe, and they also note Truman’s urgency to end the war before Soviet troops could get involved and enhance the Soviet imprint on east Asia. Most of all, historians wonder whether the subsequent Nagasaki bombing was necessary just three days after the Hiroshima bombing.

Americans like to think of themselves as virtuous — most especially during World War II. American military power helped turned back both Germany and Japan, preventing them from establishing anti-liberal empires in Europe and Asia. That paved the way for today’s relatively democratic and peaceful global order. It’s impossible today to step back into the shoes of American leaders in 1945, and it’s perhaps unfair to malign Truman with such ease from the comfort of the future.

The United States helped rebuild Japan and helped craft the democratic and constitutional institutions that govern Japan today. The two countries long ago moved on. Though Japan continues to struggle with the legacy of ‘comfort women,’ and World War II-era grievances continue to dampen relations with South Korea and China, the US-Japanese bilateral relationship is strong on multiple levels.

But it’s still important to recognize that there’s only one country in the world that’s ever used nuclear weapons in war, and that’s the United States of America. That fact is still relevant today when, for example, US officials draw lines about which countries should or should not be permitted to possess nuclear weapons. An Obama visit to Hiroshima, more than decades of START accords with Russia, would telescope to the world that an American president understands that reality, even as the work of non-proliferation continues into its eighth post-Hiroshima decade.