Hiroshima on Thursday marked the 81st anniversary of the U.S. atomic bombing of the western Japanese city, with its mayor criticizing major powers for waging wars and urging them to stop justifying the possession of nuclear weapons as a method of deterrence.

“Downplaying the inhumanity of nuclear weapons and accepting the use of force to pursue one’s own prosperity risk cycles of violent retaliation that could ultimately result in another Hiroshima or Nagasaki,” Mayor Kazumi Matsui said.

Too many political leaders still consider nuclear deterrence a realistic approach and legitimize violence, which “simply pushes a world without nuclear weapons further into the distance,” Matsui said in his peace declaration at the ceremony at the Hiroshima Peace Memorial Park. He also called on each citizen to learn lessons from the past and take action.

About 50,000 people, including representatives from some 120 countries and regions including the United States and Iran, were to attend the ceremony. A minute of silence was held while a peace bell rang out at 8:15 a.m., the time when a U.S. B-29 dropped the bomb on the city.

Prime Minister Sanae Takaichi,who attended the memorial for the first time as prime minister, said she will take “a realistic approach” toward achieving a world where nuclear weapons are never used, within the framework of the United Nations’ treaty to prevent the spread of nuclear weapons.

This year’s ceremony comes at a time of looming speculation that Takaichi’s hawkish government, which supports the idea of nuclear deterrence, may ease Japan’s postwar three non-nuclear principles when it compiles new security and defense documents later this year.

Takaichi has advocated a review of the principles for a possibility of dropping the third one — of not permitting nuclear weapons to be brought into the country.

Takaichi said Japan has maintained its postwar three non-nuclear principles, but fell short of expressing commitment for sticking with that policy into the future.

Survivors have expressed frustration and worry over growing support for the possession of nuclear weapons for deterrence by the international community, including Japan.