Polls show most Americans still consider the decision to use atomic weapons in the second World War correct, although support among women and the young is declining.
Successive United States presidents have defended the bombings, saying they helped end the war and save lives on both sides. President George HW Bush said, in 1991, they had "spared millions" of Americans.
The US has conducted more than half of the world's 2,000 nuclear tests since 1945. It maintains about 4,760 of the world's 15,700 nuclear warheads, a total that includes about 10 developed by the world's newest nuclear power, North Korea, according to the Bulletin of the Atomic Scientists.
Under US president Barack Obama, the country has reported cutting 158 strategic warheads and plans further cuts by 2018. But it also plans to spend up to $350 billion (about €319 billion) on "modernising and maintaining its nuclear forces", according to the bulletin.
Despite being the only country subjected to atomic bombs, Japan shelters under the US nuclear umbrella. Japanese politicians hint occasionally at a further step; in 2011, Shintaro Ishihara, the then governor of Tokyo, said Japan should have its own arsenal.
“People talk about the cost and other things, but the fact is that diplomatic bargaining power means nuclear weapons,” he said. “All the members of the [United Nations] Security Council have them.”
