US Ambassador to the United Nations, Linda Thomas-Greenfield, visited the Atomic Bomb Museum in the Japanese city of Nagasaki on Friday.
Thomas-Greenfield has become the first US ambassador to the UN to visit the atomic-bombed city.
US officials say that the ambassador visited the Peace Park in Nagasaki on Friday afternoon and laid flowers in front of the Peace Statue.
Thomas-Greenfield viewed exhibits at the museum for about 25 minutes, guided by Nagasaki City Mayor Suzuki Shiro, the museum's director Inoue Takuji and atomic bomb survivor Tomonaga Masao.
She wrote a massage on a guest book on behalf of the US administration of President Joe Biden.
The ambassador wrote, "Today, I am reminded of our responsibility -- as governments, as allies, and as human beings -- to end the scourge of war, once and for all."
Thomas-Greenfield then made a speech. She said, "Just now at the Atomic Bomb Museum, I saw the unspeakable devastation and destruction of life." She said it was a very powerful reminder that nuclear weapons should never be used again.
She also said that people must continue to work together to create an environment for nuclear disarmament, and continue to prevent the spread of nuclear weapons in every corner of the world.
The envoy added that countries that already have these weapons must continue to pursue arms control.
US officials say that the ambassador later attended an event to exchange views with students from state-run Nagasaki University and the prefectural University of Nagasaki.
Tomonaga, who guided Thomas-Greenfield, said that he explained medical matters related to the atomic bombing, and that the ambassador was surprised to hear the effects of the atomic bombing continue for a lifetime.
Tomonaga also said that the ambassador told him that the United States will do what it can to create a world without nuclear weapons.
He said Thomas-Greenfield is seriously hoping that Nagasaki will be the last place to experience a nuclear bombing.