The U.S. government and the International Atomic Energy Agency have questions about a military site in Iran with suspected ties to the country's nuclear program, ABC News has learned.
Iran's Parchin complex — covering approximately 15 square miles and located about 19 miles southeast of Tehran — is known as a center for the production of conventional ammunition and explosives. A State Department official has confirmed the United States suspects nuclear activity at some of its facilities. The suspicions focus on possible testing of high explosives.
"Parchin is the center of Iran's munitions industry and home to Iran's oldest ammunitions factory, founded before World War II," said John Pike, directory of GlobalSecurity.org, an organization that seeks to reduce reliance on nuclear weapons.
"It would be the logical place for Iran to conduct weaponization work on an atomic bomb and the logical place for us to look for such work," he said.
Images of Parchin, obtained exclusively by ABC News, show a building within the facility's high-explosive test area that could permit the testing of especially large explosions, including those relevant to the development of a nuclear weapon.
"While the imagery is not definitive, it raises enough questions that Iran should allow IAEA inspection of the site to alleviate concerns," said Corey Hinderstein, deputy director of the Institute for Science and International Security — a nonprofit, nonpartisan institution that seeks to inform the public about science and policy issues affecting international security.
An affiliation between Parchin and Iran's nuclear program had not been previously suspected, and the site has not been inspected by IAEA experts. A recent report by the atomic agency did not mention the location, but ABC News has learned the IAEA asked Iran privately to visit the facility more than a month ago. U.S. and U.N. sources say Iran has ignored the request.
High explosives are used in the detonation of a nuclear weapon. In an implosion-type device, for example, a shell of chemical high explosives surrounds the nuclear material — either uranium or plutonium — and is compressed through multiple, precisely timed detonations.
To ensure that the nuclear material is compressed effectively, high-speed cameras and other sensors are used to record exactly the timing of the detonations and how the nuclear material reacts to the triggers.
On the basis of image analysis alone, it is difficult to distinguish between the testing of conventional high explosives and those necessary for the development of a nuclear weapon.
"Neither the design of the facility nor the nature of the tests is unique to nuclear weapons," said Jay C. Davis, former head of the Defense Threat Reduction Agency at the U.S. Department of Defense. "This is always a problem in trying to detect nuclear activity, and one that only on-site inspection can establish."
Davis added that environmental sampling done by IAEA inspectors could detect the presence of byproducts used in the testing of high explosives for a nuclear weapon.
"A surrogate material, such as depleted uranium, for example, could be used in such testing and would be detectable via sampling," he said.
The IAEA, the United Nations' nuclear arm, has been meeting this week at its headquarters in Vienna, Austria, to discuss Iran's nuclear program. The United States has proposed a strongly worded resolution that would call on Iran to provide full disclosure of its nuclear activities to the IAEA, or face action by the U.N. Security Council, which could impose sanctions.
At today's meeting of IAEA's governing board, both the United States and the European Union sought a commitment from Iran to stop enrichment. But Hossein Mousavian, Iran's chief envoy to the meeting, suggested his country would not yield to threats of Security Council action.
The Iranian government did not respond to ABC News' questions about Parchin.
For more information, visit www.isis-online.org and www.globalsecurity.org.