TOKYO (AP) — Nagasaki marked on Sunday the 81st anniversary of the U.S. atomic bombing of the southwestern city, as the mayor called nuclear weapons “absolute evil,” denounced growing support for nuclear deterrence and called on the Japanese government to adhere to its three postwar non-nuclear principles.

The anniversary coincided with Japanese Prime Minister Sanae Takaichi ’s government revising the country’s defense policy to further bolster the military’s offensive capability. Speculation has risen about whether Takaichi, who supports nuclear dissuasion, may allow nuclear weapons to be brought into the country, going against the third non-nuclear principle.

Mayor Shiro Suzuki said that while some countries argue the possession of nuclear weapons helps deter potential attackers, the atomic bombings of Hiroshima and Nagasaki had demonstrated that humans can cross the line.

“The theory of nuclear deterrence is extremely dangerous and fragile. Nuclear weapons are not a ‘necessary evil’ but an ‘absolute evil,’ and can never coexist with humanity,” Suzuki said. “To all leaders of the nuclear states and nations relying on nuclear deterrence, you must face the reality that the more you rely on nuclear deterrence, the more you increase the risk of a nuclear war.”

The United States launched the Nagasaki attack on Aug. 9, 1945, killing 70,000 by the end of that year, three days after the bombing of Hiroshima that killed 140,000. Japan surrendered on Aug. 15, 1945, ending World War II and the nearly half-century of aggression across Asia.

Representatives from more than 90 countries attended the ceremony at the Peace Park on Sunday and observed a moment of silence at 11:02 a.m. when a B-29 dropped a plutonium bomb, known as “Fat Man.”

Suzuki singled out the Japanese government, demanding it uphold Japan’s war-renouncing Constitution, attend the Treaty on the Prohibition of Nuclear Weapons review conference later this year and stick to the three non-nuclear principles.

Takaichi supports the first two principles of not possessing and developing nuclear weapons.

The prime minister, who attended Sunday’s ceremony, reiterated her policy of taking “a realistic and pragmatic approach” toward achieving a world without nuclear weapons. As she did in Hiroshima, Takaichi remained ambiguous about the three non-nuclear principles and only reiterated that Japan currently maintains the policy.

Takaichi, in her speech at the ceremony, did not mention the Treaty on the Prohibition of Nuclear Weapons, which Tokyo has refused to sign because Japan is under the protection of the U.S. nuclear umbrella.

She later told reporters that Japan’s policy is to work within the Nuclear Nonproliferation Treaty, and that her government will decide what to do with the treaty based on what’s most effective to ensure the country’s national security and push forward nuclear disarmament.

Survivors have expressed frustration and criticized the Japanese government’s support for nuclear deterrence for being insincere. Growing concern about Takaichi’s possible easing of the non-nuclear principles has prompted protests by the survivors, or hibakusha, in Hiroshima and Nagasaki.

The number of survivors has fallen to 91,105, about a quarter of the original number, with their average age exceeding 86. Survivors worry about fading memories, as the youngest of the survivors were too young to clearly recall the attack.