Taking place in the first city to suffer an atomic bombing, this weekend’s Group of Seven summit has a certain poetry.

The choice of Hiroshima as the venue is more than Japan’s leader, Fumio Kishida, picking his home constituency. The country holds the G7 presidency just as the eight-decade taboo on the use of nuclear weapons feels closer than ever to being broken due to Russia’s invasion of Ukraine. The prime minister has a lifelong commitment to denuclearization, stating in his 2021 book that "as a Japanese politician from Hiroshima, it is my duty to continue to speak about the inhumanity of nuclear weapons.” He’ll spend much of this weekend promoting their complete elimination.

But the timing and location have an irony, too. It’s also Kishida who is overseeing the greatest expansion of Japanese military power since the end of World War II, a push that’s moving the country even closer to the U.S. — which is, after all, the greatest nuclear power in the world. It’s the only nation to have used such weapons in conflict, and its nuclear umbrella is more vital than ever as Japan’s security shield.

Japanese leaders have wrestled with this contradiction for years, leading to compromises such as the country’s three principles of not possessing, producing or permitting nuclear weapons on its soil. But Russia’s invasion of Ukraine and the looming threat of a conflict over Taiwan has made Tokyo’s commitment to peace an ever-smaller needle to thread.

In U.S. President Joe Biden, Kishida has a counterpart who believes in old-fashioned diplomacy and a rules-based order, and has displayed the kind of nerve on Chinese expansionism that was singularly lacking when he was Barack Obama’s vice president and Beijing was militarizing islands in the South China Sea. U.S. support is one of the reasons Kishida has been able to lift a decades-old cap on defense spending.

Until recently, such a move would have been met with suspicion across the Pacific. Now, the U.S. ambassador has hailed it as starting a "new era in the defense of democracy.” While the prime minister’s office may not have been happy with a Time magazine cover featuring Kishida in which said he wanted to "abandon decades of pacifism,” the premier has nonetheless found himself at a point in time when Japan’s geopolitical significance is surging.

With the G7 taking place in a country that borders Russia and would be on the front lines of a conflict over Taiwan, security will be at the top of the agenda. And while Kishida will seek agreement on a statement supporting the elimination of nuclear weapons, he’ll know that progress on denuclearization has rarely seemed more distant.

Russia’s invasion of Ukraine has raised the stakes. Dmitry Medvedev, the deputy chair of Russia’s Security Council, threatened earlier this year that the West’s move to supply weapons to Ukraine was bringing "nuclear apocalypse” closer. Kyiv — which briefly had the world's third-largest nuclear arsenal — gave up the weapons on its territory in 1994 after the fall of the Soviet Union, in exchange for security guarantees.

It is incumbent on G7 leaders to make a strong commitment to continued military and financial support for Ukraine to ensure there isn’t a resurgent interest in nuclear weapons as a way of safeguarding sovereignty and independence. In the case of North Korea that’s too late, with Pyongyang undeniably having become a fully fledged nuclear power over the past decade. And that in turn has led South Korean President Yoon Suk Yeol to recently suggest his country might need to develop atomic weapons, though he has since backed off the idea following a visit to Washington.

The G7 leaders will have little difficulty finding common ground on Ukraine, with Kishida showing a much stronger stance than his predecessors. And although he warned last year that "Ukraine today may be East Asia tomorrow,” finding consensus on the crucial issue of China’s increasing assertiveness through the region could be trickier.

The summit in Asia represents a chance to convince the likes of French President Emmanuel Macron and German Chancellor Olaf Scholz, both of whom have made controversial trips to Beijing since the last G7 meeting, of the risks. But more concrete steps might be trickier now that the Quad meeting, set to take place in Sydney, was cancelled after Biden elected to return to the U.S. for debt ceiling talks. The leaders, which include Australian Prime Minister Anthony Albanese and India’s Narendra Modi as well as Biden and Kishida, will speak in Hiroshima instead.

The Hiroshima summit also puts into perspective how quickly things have changed since the last time G7 leaders gathered in Japan. At Ise-shima in 2016, China wasn’t even mentioned in the joint statement — and now, Beijing’s economic coercion is expected to be a key concern noted in this year’s communique. Seven years ago, Japan was still shaken by domestic protests over security legislation enacted in 2015, in stark contrast to the broad support for his military expansion plans that Kishida enjoys now.

Back then, Obama became the first sitting U.S. president to visit Hiroshima, accompanied by Kishida, for whom it was a coming of age on the international stage. Biden’s visit, with other world leaders, may well lack that gravitas. Kishida seems unlikely to get concrete steps toward his denuclearization goal. But nonetheless, his homeland — a city destroyed and rebuilt by the decisions and mistakes of leaders past — will be a poignant backdrop to a crucial meeting of their successors.

Gearoid Reidy is a Bloomberg Opinion columnist covering Japan and the Koreas.