Biden and other leaders visited the Hiroshima Peace Memorial Museum before laying wreaths at an outdoor memorial just steps away from the “bomb dome,” the only structure left standing after the atomic blast and a striking symbol of the most destructive force ever created by man.

Japanese Prime Minister Fumio Kishida chose to host the annual meeting of the world’s leading democracies in Hiroshima to affirm the importance of nuclear disarmament and non-proliferation. Moscow’s saber-rattling over nuclear weapons, China’s growing hawkishness toward Taiwan and North Korea’s revived missile test program are stoking new fears about another nuclear holocaust in our time.

“The existing nuclear security architecture is being shaken,” said Kyoko Imai, a fellow at the Atlantic Council’s Indo-Pacific Security Initiative.

The G7’s rejection of any challenges to that status quo is, Imai continued, “not just a message for Vladimir Putin,” the Russian president, but also for Chinese leader Xi Jinping and North Korea’s Kim Jong Un. “The war in Ukraine has clearly shown that regional crises have global ramifications,” Imai said.

While the G7 has responded to Russia’s war in Ukraine with conviction and cohesion, differences have emerged over member countries’ varying willingness to send more advanced weaponry to Kyiv. Germany, long reluctant about defense posturing and averse to military conflict, just announced €2.7 billion (close to $3 billion) in additional assistance for Ukraine, its largest package since the war began.

Zelenskyy, whose military is under growing pressure to turn the tide on the battlefield in the coming months, has asked Western allies to give it U.S.-made F-16 fighter jets, which Washington has thus far been unwilling to provide.