This article is by William J. Broad, Mark Mazzetti and David E. Sanger.
WASHINGTON — When President Obama stood last week with the leaders of Britain and France to denounce Iran’s construction of a secret nuclear plant, the Western powers all appeared to be on the same page.
Behind their show of unity about Iran’s clandestine efforts to manufacture nuclear fuel, however, is a continuing debate among American, European and Israeli spies about a separate component of Iran’s nuclear program: its clandestine efforts to design a nuclear warhead.
The Israelis, who have delivered veiled threats of a military strike, say they believe that Iran has restarted these “weaponization” efforts, which would mark a final step in building a nuclear weapon. The Germans say they believe that the weapons work was never halted. The French have strongly suggested that independent international inspectors have more information about the weapons work than they have made public.
Meanwhile, in closed-door discussions, American spy agencies have stood firm in their conclusion that while Iran may ultimately want a bomb, the country halted work on weapons design in 2003 and probably has not restarted that effort — a judgment first made public in a 2007 National Intelligence Estimate.
The debate, in essence, is a mirror image of the intelligence dispute on the eve of the Iraq war.
This time, United States spy agencies are delivering more cautious assessments about Iran’s clandestine programs than their Western European counterparts.
The differing views color how each country perceives the imminence of the Iranian threat and how to deal with it in the coming months, including this week’s negotiations in Geneva — the first direct talks between the United States and Iran in nearly 30 years.
In the case of the plant outside Qum, designed for uranium enrichment, some nuclear experts speculate that it is only part of something larger. But a senior American official with access to intelligence about it said he believed the secret plant was itself “the big one,” but cautioned that “it’s a big country.”
This distinction has huge political consequences. If Mr. Obama can convince Israel that the exposure of the Qum plant has dealt a significant setback to the Iranian effort, he may buy some time from the Israelis.
The officials spoke on the condition of anonymity because they were discussing classified intelligence assessments.
Uranium enrichment — the process of turning raw uranium into reactor or bomb fuel — is only one part of building a nuclear weapon, though it is the most difficult step. The two remaining steps are designing and building a warhead, and building a reliable delivery system, like a ballistic missile.
American officials said that Iran halted warhead design efforts in 2003, a conclusion they reached after penetrating Iran’s computer networks and gaining access to internal government communications. This judgment became the cornerstone of the 2007 intelligence report, which drew sharp criticism from Europe and Israel, and remains the subject of intense debate.
Disagreeing with the Americans, Israeli intelligence officials say they believe that Iran restarted weapons design work in 2005 on the orders of Ayatollah Ali Khamenei, the supreme leader. The Americans counter that the Israeli case is flimsy and circumstantial, and that the Israelis cannot document their claim.
German intelligence officials take an even harder line against Iran. They say the weapons work never stopped, a judgment made public last year in a German court case involving shipments of banned technology to Tehran. In recent interviews, German intelligence agencies declined to comment further.
Rolf Mowatt-Larssen, the former head of intelligence at the Department of Energy and a nuclear expert who worked for the C.I.A., said that the apparent differences of opinion among the world’s intelligence agencies might boil down to differences of interpretative style, or what he called “tradecraft.”
“It’s often tradecraft that gets us bollixed up,” he said in an interview. “It comes down to interpreting the same data in different ways, in looking at the same information and coming up with different conclusions.”
Some Israeli and European officials say the Americans are being overly cautious, having been stung by the Iraq intelligence debacle. The Americans deny this, insisting they are open-minded. One American intelligence official said the view of Iran’s weapons design program, “like every analytic judgment, is constantly checked and reassessed in light of new information, which comes in all the time.”
Each country bases its view on a combination of satellite imagery, human spies and electronic eavesdropping. And they do not necessarily share it all with one another or with the International Atomic Energy Agency, an investigative arm of the United Nations.
This has created plenty of bad blood with the United Nations agency. The departing chief of the I.A.E.A., Mohamed ElBaradei, recently argued that the case for urgent action against Iran was “hyped.” He acknowledged, however, that Iran has refused, for two years, to answer his inspectors’ questions about evidence suggesting that it was working on weapons design.
Now some European powers who fought with President George W. Bush over the evidence on Iraq — and were later vindicated by the failure to find unconventional weapons — are pressing Dr. ElBaradei to reveal what his agency has collected on its own, through regular inspections in Iran.
“Why doesn’t he provide us with the annexes of his report?” Bernard Kouchner, France’s foreign minister, asked last month, referring to material United Nations inspectors are believed to have compiled for internal discussions. Mr. Kouchner said those annexes contained “elements which enable us to ask questions about the reality of an atomic bomb. There are issues of warheads, of transport.”
Western intelligence officials now want to determine whether there are even more secret enrichment sites. Defense Secretary Robert M. Gates dodged the question of whether there were additional sites during a television appearance over the weekend. Washington has said there may be more than a dozen sites involved in the nuclear program, though there have been no public indications as to what they are used for.
Graham Allison, the author of “Nuclear Terrorism” and a Harvard professor who focuses on proliferation, said he could not conceive of Iran’s building only one such site.
“How likely is it that the Qum facility is all there is? Zero. A prudent manager of a serious program would certainly have a number of sites,” he said.
After all, Mr. Allison said, the lesson Iran took away from Israel’s destruction of an Iraqi reactor more than 25 years ago is to spread facilities around the country.