The mayors of Hiroshima and Nagasaki requested Tuesday that U.S. President Joe Biden visit their cities during his expected trip to Japan later this year, as Russia has threatened to use nuclear weapons in its ongoing invasion of Ukraine.

Hiroshima Mayor Kazumi Matsui and Nagasaki Mayor Tomohisa Taue, whose cities were attacked with atomic bombs during World War II, made the request in a meeting with Japanese Foreign Minister Yoshimasa Hayashi in Tokyo.

Biden is expected to visit Japan when the country hosts a summit meeting of the so-called Quad grouping of democracies comprising Australia, India, Japan and the United States sometime before June.

Nagasaki Mayor Tomihisa Taue (L), Hiroshima Mayor Kazumi Matsui (R) and Foreign Minister Hayashi Yoshimasa (C) hold a request from the two mayors in Tokyo on March 22, 2022. (Kyodo

"Visits by dignitaries to the places that suffered atomic bombings are crucial," Hayashi said at the outset of the talks. "It is very important for the international community to see the naked reality of an atomic bombing as that would mark the start of all efforts toward nuclear disarmament."

Russian President Vladimir Putin placed his country's nuclear forces on high alert earlier this month as Ukrainians put up resistance against Russian aggression and the United States and its allies rolled out economic sanctions against Moscow.

"With the (Russian) invasion of Ukraine, statements have been made about the possible use of nuclear weapons," Matsui said. "There is a growing sense of crisis."

Taue said, "I think it would be significant to have President Biden issue a message."

Before the meeting, the two mayors met U.S. Ambassador to Japan Rahm Emanuel and urged Biden to visit their cities.