Richard Nephew, a sanctions expert and a former member of the US team of negotiators, said he believes the biggest potential stumbling block in Iran's nuclear talks is whether international inspectors will have access to Iranian military bases.
Iranian officials have declared that such access would violate the Islamic Republic's sovereignty and would never be acceptable.
But western governments view access to the bases as an essential part of any deal because of the need for full transparency to ensure that Iran is not secretly working on a nuclear weapon, the Los Angeles Times on Tuesday quoted Nephew as saying.
Tehran denies the allegation that it may be seeking to develop a nuclear weapons capability under the guise of a civilian program, saying the work is solely for peaceful applications such as generating electricity.
"If the political environment in Tehran can't support agreement on this, things will fall apart," Nephew said. He said he believed the Obama administration would not accept a deal without full transparency because such an agreement could not be sold in the United States or in European capitals.
"This is nonnegotiable, from Washington's point of view," he said.
But the Iranians also feel strongly about it, Nephew said, because access to bases would mean that inspectors would be peering at Iran's defenses at a time when US officials are saying publicly that they reserve the right to bomb the country if necessary to halt its nuclear program.
