Prime Minister Fumio Kishida escorted the U.S. ambassador to his hometown Hiroshima on Saturday to pay respects to atomic bombing victims and warned that the world is again facing threats of nuclear attacks stemming from Russia's invasion of Ukraine.

“As we face a possibility of Russia’s use of nuclear weapons as a realistic concern, I felt strongly (as leader of) the world’s only country to have suffered atomic attacks that we should never allow threats or use of nuclear weapons,” Kishida told reporters after a tour of the peace park and the museum with Ambassador Rahm Emanuel.

“The tragedy should never be repeated,” Kishida said.

Leaders from the Group of Seven countries on Thursday urged Russia not to use biological, chemical or nuclear weapons in its war on Ukraine. That prospects was raised when Russian President Vladimir Putin in February ordered his nation’s nuclear forces put on high alert over tensions with the West.

The Aug. 6, 1945, atomic bombing by the United States killed about 140,000 people and nearly destroyed Hiroshima. Three days later, a second U.S. atomic bomb dropped on Nagasaki killed 70,000 more, before Japan surrendered six days later.

Russia’s invasion of Ukraine “highlights the harsh road toward achieving a world without nuclear weapons,” Kishida said. “As prime minister from Hiroshima, I must firmly send a message (of peace) to the rest of the world.”

Kishida, however, has been pushing to bolster Japan's military budget and capability amid growing threats from China, North Korea and Russia. He says his realistic approach is to protect lives while seeking to achieve the ideal for the future.

About 3,000 Russian troops were conducting drills on the disputed northern islands, according to media reports, first since Russia's Foreign Ministry said it was suspending peace treaty talks with Japan, citing Tokyo's sanctions against Moscow.

Russia has also increased naval activity around Japan, which Japanese officials say is meant to project Moscow's military strength.

Kishida and Emanuel visited the Peace Memorial Museum and laid flowers to the victims at the Hiroshima Peace Memorial Park.

In 2016, Kishida accompanied then-President Barack Obama on his visit to Hiroshima, where he made a pledge to seek a world without nuclear weapons and met with several atomic bombing survivors.

A visit to Hiroshima by Emanuel, known for his close ties to President Joe Biden, is raising hopes for a similar presidential visit.

Emanuel said that he cannot speak for Biden but there is a possibility.

“I think as a friend I can say if he makes it here to Japan I know he'll want to visit one of the two cities, but not both,” he said.

The mayors of Hiroshima and Nagasaki have requested that Biden make a similar trip to their cities during his visit to Japan to attend a summit of Quad nations, which also includes Australia and India, expected in late April. Quad, or the “Quadrilateral Security Dialogue,” is an Indo-Pacific alliance established in 2007.