U.S. Declares Size of Nuclear Arsenal

The Obama administration for the first time made public the extent of the U.S.’s atomic-weapons arsenal, as the U.S. and Iran dueled for the international backing of their strategic agendas.

Secretary of State Hillary Clinton and Iranian President Mahmoud Ahmadinejad both addressed a special U.N. conference on the global nuclear nonproliferation regime on Monday as Washington pushes for a new round of sanctions against Iran for its nuclear work.

Mrs. Clinton and Mr. Ahmadinejad sought to define the other nation’s nuclear capability as the principal threat to international stability. The Iranian president charged Washington with leading a skewed international system that seeks to deny peaceful nuclear power to developing nations while allowing allies such as Israel to stockpile atomic arms.

“The first atomic weapons were produced and used by the United States,” Mr. Ahmadinejad said in a 35-minute morning speech. “This seemed … to provide the United States and its allies with the upper hand. However, it became the main source of the development and spread of nuclear weapons.”

Mrs. Clinton followed in the afternoon by declaring, to the surprise of some delegates, that the U.S. was announcing the size of its nuclear arsenal, as well as the number of atomic weapons it has destroyed from its arsenal; the Pentagon announced the figures in a news conference on Monday.

U.S. officials have been working for almost a year to undercut Tehran’s charges about Washington’s nuclear threat by bringing transparency to the U.S. program as well as by reducing its numbers. In April, the U.S. and Russia signed a Strategic Arms Reduction Treaty that lowers the numbers of deployed American and Russian nuclear weapons to their lowest levels since the 1950s. The U.S. also hosted a nuclear security conference in Washington last month.

“So for those who doubt that the U.S. will do its part on disarmament: This is our record—these are our commitments—and they send a clear signal,” Mrs. Clinton told the conference.

The Pentagon said the U.S. had a total of 5,113 nuclear warheads in its stockpile as of Sept. 30, plus a few thousand more that had been retired but still needed to be dismantled. Between fiscal years 1994 and 2009, the U.S. dismantled 8,748 nuclear warheads. At its peak at the end of fiscal year 1967, the U.S. had 31,255 warheads, the Pentagon said.

It was the first time the U.S. has disclosed those figures, which had been previously regarded as highly classified. A senior defense official said at a Pentagon briefing that the stockpile had been reduced by 75% since 1989 and roughly 84% since 1967.

Also on Monday, Mrs. Clinton said Washington will continue to increase funding and technical support for countries pursuing civilian nuclear power while adhering to safeguards that prevent the development of military applications.

After Mr. Ahmadinejad had charged the U.S. with double standards by tacitly supporting Israel’s assumed nuclear program, Mrs. Clinton said the Obama administration supported a nuclear weapons-free zone in the Mideast once progress is made in pushing forward the Arab-Israeli peace process. She added that the administration would support such zones in Africa and the South Pacific.

The Obama administration is in the final stages of a global push to enact new sanctions on Iran for its nuclear work. Mrs. Clinton on Monday met nations seen as still on the fence on the sanctions issue, such as Brazil. And President Barack Obama released a statement claiming the course of Iran’s nuclear work could define whether the Nuclear Nonproliferation Treaty, the subject of the monthlong U.N. conference, survives into the 21st century. The NPT holds existing weapons states to reduce their arms and other countries not to pursue them.

Mr. Ahmadinejad, in his speech, called for a vast remaking of the global institutions guarding the development of nuclear technologies, while denying his own nation was seeking atomic weapons.

British, American and French diplomats walked out of his speech in quick succession about 10 minutes into its delivery.

The U.S. release of nuclear data reverses decades of Cold War doctrine that concluded that the U.S.’s national security could be threatened if Washington’s adversaries knew the size and status of its nuclear arsenal. China and Russia have made similar arguments in denying U.S. calls for them to provide greater transparency.

The U.S.’s nuclear program has been regularly tracked by specialty websites. Some voiced little surprise with the released numbers.

The release of the nuclear data was vigorously debated inside the White House and Pentagon, according to U.S. officials. Mrs. Clinton stressed Monday that the conclusion was that it served the U.S.’s national security interests by placing the issue of transparency back on the shoulders of nations such as Iran and North Korea.

Conservative critics quickly attacked the release of the nuclear data. “From a strategic standpoint I think the problem is that it becomes yet another ax to grind against the United States: You have X and we only have Y, and … we are not going to disarm until you have Y,” said Danielle Pletka, vice president of the American Enterprise Institute, a conservative Washington think tank.