Tasnim � Iran�s Foreign Ministry spokesman slammed the US government for refusing to shoulder responsibility for the atomic bombings of two Japanese cities of Hiroshima and Nagasaki back in 1945.

�Maybe nothing ever happens once,� Seyed Abbas Mousavi tweeted on Sunday night, quoting a line from American writer and poet, William Faulkner

�If an incident happens once or more (it could happen again), the US atomic bombardment was more than once; Hiroshima and Nagasaki bombardment still lingers in the minds of the Japanese and the world',� he added.

The culprit behind both cases is a government which refuses to shoulder responsibility, and instead claims to be a pioneer in countering weapons of mass destruction, Mousavi deplored.

The Iranian spokesperson posted the tweet on the occasion of the 75th anniversary of American B-29 bomber Bockscar's dropping of a 4.5-ton plutonium bomb dubbed �Fat Man� on the Japanese port city of Nagasaki, killing more than 70,000 of its residents. Many people died immediately while others succumbed to their injuries or radiation-related illnesses weeks, months, and years later.

The atomic bombing of Nagasaki took place three days after the US dropped another atomic bomb on the Japanese city of Hiroshima on August 6, which killed 140,000 people.

Japan on Sunday marked the 75th anniversary of the US atomic bombing of Nagasaki, calling for a ban on nuclear weapons.

At the ceremony, which was also attended by Japanese Prime Minister Shinzo Abe, the mayor of Nagasaki, Tomihisa Taue, urged world leaders to ban nuclear weapons.