The U.S. Government Printing Office (GPO) published last month a detailed 268-page dossier disclosing the addresses and specifications of hundreds of U.S. nuclear-weapons-related facilities, laboratories, reactors and research activities, including the location of fuel for bombs.
The document, which was removed from the Web on Tuesday, is a draft declaration of facilities to the International Atomic Energy Agency (IAEA), the U.N. nuclear watchdog, required under agreements that the United States signed in 2004. It is considered highly sensitive though technically not classified.
The vice chairman of the Senate Select Committee on Intelligence, Christopher S. Bond, Missouri Republican, said the disclosure revealed "a virtual treasure map for terrorists."
A Pentagon official with knowledge of the situation said the Pentagon is "clearly concerned about the situation."
"Any information that could be used by potential adversaries to attack infrastructure in the U.S. is of concern to us," said the official, who spoke on the condition of anonymity because of the sensitive nature of the issue. "While much of this information is available by any number of means, one should be cautious when it is placed in the aggregate, in one source, and that creates security concerns."
Damien LaVera, a spokesman for the National Nuclear Security Administration, said the report had been reviewed by the departments of Energy, Defense and Commerce and the Nuclear Regulatory Commission "to ensure that no information of direct national security significance would be compromised."
"This declaration is an important demonstration of the administration's support for the IAEA and the nuclear nonproliferation regime," he said, but added, "We would have preferred it not be released."
The National Nuclear Security Administration is a division of the Department of Energy charged with securing nuclear infrastructure.
David Albright, a former nuclear inspector and president of the Institute for Science and International Security, a Washington think tank, said, "It's a mistake, and it should not have been released, especially not with 'safeguards/confidential' still written on it."
"The problem is there are a few places where it shows rooms inside of buildings where fissile material is located," he said. Although terrorists still would have difficulty penetrating U.S. security to acquire the material, he said, the disclosure was potentially a violation of U.S. law.
"If we had published it, all hell would break loose."
The report did not include locations of missile silos, he said.
Mr. Bond said he and his staff were trying to figure out how the document ended up being published.
"Our best understanding is that this was sent to GPO by staffers of the House leader," he said. "If we are going down this road, if we have a culture now where we go ahead and disclose everything, especially when it comes to national security, that is playing fast and loose with the safety of Americans."
Mr. Bond also said that it was possible that the security officer on the House Foreign Affairs Committee was "lax" in not stopping the publication of the document.
Lynne Weil, a spokeswoman for the House Foreign Affairs Committee, said, "The committee reviewed the document from the Government Printing Office and neither published it nor had control over its publication by the GPO."
She said the committee would investigate what happened.
GPO officials could not be reached for comment Tuesday because their office had already closed.
The pages of the document, which are marked "highly confidential, safeguards sensitive," appeared on the GPO Web site, www.gpo.gov. An accompanying letter from President Obama dated May 5 said the United States "regards this information as 'sensitive but unclassified.'" The document was sent to the House parliamentarian earlier this month and was forwarded to the GPO, said three congressional staffers who spoke on the condition they not be named because of the nature of the issue.
Two national security specialists said the disclosure did not pose a national security risk.
Steven Aftergood, who runs the Project on Government Secrecy for the Federation of American Scientists, praised the decision to publish the dossier.
"It is significant on a few different levels," said Mr. Aftergood, who first wrote about the publication Monday on Secrecy News, his Web site.
"If you set out to compile a list of these facilities, you could do it, none of them are classified, none of them are unacknowledged, all of them have a measure of security, no one will be able to walk off the street and penetrate any of these facilities. Until we have insurrection in American cities, this information belongs in the public domain," Mr. Aftergood said.
Nonetheless, the publication of a country's declaration of facilities to the IAEA is unusual. Portions of Iraq's declaration under Saddam Hussein leaked to the public. Otherwise, Mr. Aftergood said, he was unaware of any other time that a country's disclosure had been released.
The Pentagon official said that after the Sept. 11, 2001, terrorist attacks, U.S. nuclear installations beefed up physical security, but "we need to be mindful of the type of information that we make available through the Internet and we don't want to do anything that might highlight potential vulnerabilities."
Retired Army Special Operations Maj. Gen. Tim Haake said disclosing any information on the "location or disposition of our nuclear arsenals or supporting information being made freely available in one document is a threat on several levels."
A U.S. adversary "like North Korea or even Iran" could use the information to plan future attacks, he said.
"At a lower level, it allows people with nefarious intentions to target employees at the facilities, for infiltration," Gen. Haake said. "Now that they know where these locations are, they don't have to break in, they can target things and people going in and out of any of these facilities. Some of the larger facilities have always been known, but it's the smaller facilities that we're concerned about and those assets that support our nuclear arsenal. Just think of how much money will we need to invest to enhance security at these sites that are now so exposed in this full document."
Henry Sokolski, executive director of the Non-Proliferation Policy Education Center, a Washington think tank, said most of the information disclosed in the document was related to Department of Energy programs touted in the past as developing methods to make it harder to divert nuclear material for weapons.
"It is a bit ironic that nobody wanted this information to be made public," Mr. Sokolski said. "Most of the listed programs are advanced nuclear fuel cycle and reactor initiatives that the Department of Energy sold to the [Capitol] Hill claiming they would vastly reduce the possibility of terrorists being able to divert nuclear bomb material from the commercial nuclear sector. Apparently, some people don't think they are all that safe. If this is so, it might make sense to shut them down."
Barbara Slavin contributed to this report.