Assessing Iran, but Thinking About Iraq WASHINGTON - At the nation's top spy agency, the ghosts of Iraq are never far away. One C.I.A. analyst who had helped develop some of the intelligence about Saddam Hussein's supposed weapons of mass destruction had a breakdown months after the Iraq war began; he had participated in the post-invasion hunt there that found the weapons did not exist. When he eventually was given a new assignment assessing Iran's nuclear program, he confided a fear to colleagues: that the intelligence community might get it wrong again. "He felt enormous guilt that he had gotten us into the war," said one former official who worked with the analyst. He was afraid it was going to be déjà vu all over again. Today, analysts and others at the C.I.A. who are struggling to understand the nuclear ambitions of Iran are keenly aware that the agency's credibility is again on the line, amid threats of new military interventions. The intelligence debacle on Iraq has deeply influenced the way they do their work, with new safeguards intended to force analysts to be more skeptical in evaluating evidence and more cautious in drawing conclusions. Former intelligence officials say that this shows appropriate vigilance in dealing with often murky information, while some detractors argue that the agency is not just careful but also overly skittish on Iran, reluctant to be blamed for any findings that might lead the United States to bloodshed. "For a lot of people in the intelligence community, there is a feeling that they don't want to repeat the same mistake," said Greg Thielmann, a former State Department intelligence analyst who resigned to protest what he considered the Bush administration's politicization of the prewar Iraq intelligence. "The intelligence community as a whole has better practices now partly because of the scar tissue they still have from Iraq," added Mr. Thielmann, now a senior fellow at the Arms Control Association in Washington. Paul Pillar, a former senior C.I.A. analyst on the Middle East, says he believes that analysts are guided by the facts in making their assessments about Iran, but that they almost certainly have Iraq weighing on them. "Because intelligence officials are human beings, one cannot rule out the possibility of the tendency to overcompensate for past errors," said Mr. Pillar, now the director of graduate studies at the Security Studies Program at Georgetown University. Top intelligence officials have said that analysts believe that Iran has been moving to expand its infrastructure and technological ability to become a nuclear power, but that the Iranian leadership has not made a decision to build an atomic bomb. Current and former senior American officials acknowledge, though, that there are significant gaps in their knowledge, and that they may not be able to quickly detect any decision to restart Iran's weapons program, which they concluded had been halted in 2003. After the misjudgments on Iraq, the C.I.A. and other intelligence agencies imposed new checks and balances, including a requirement that analytical work be subjected to "red teaming." That means a group of analysts would challenge the conclusions of their colleagues, looking for weaknesses or errors. The intelligence community also now requires that analysts be told much more about the sources of the information they receive from the United States" human and technological spies. Analysts were left in the dark on such basic issues in the past, which helps explain why bogus information from fabricators was included in some prewar intelligence reports on Iraq. And, when they write their reports, they must include better attribution and sourcing for each major assertion. "I think the Iraq experience gave them thicker skins," said one former senior intelligence official, who like several others quoted in this article would speak only on the condition of anonymity about internal agency matters. There was a lot of work done to tighten up the tradecraft. Unlike the prelude to the Iraq war, when many critics accused Bush White House officials of cherry-picking the intelligence to conform to their policy, some outside analysts say they do not see evidence of the Obama administration pushing intelligence officials to come up with predetermined answers. "The intelligence was so heavily politicized on Iraq," said Joseph Cirincione, the president of the Ploughshares Fund, a global security foundation. The higher up the chain in the government the intelligence reporting went, the more it got massaged, and the doubts and caveats got removed. But now, he said, "I haven't heard any complaints about the administration pressuring the intelligence community to tilt the intelligence." He added that while conservative political leaders in the United States and Israel had complained about the intelligence assessments on Iran, such outside criticism did not have the same impact it would coming from the White House. "It's one thing to have the prime minister of another country come to town and say time is short, but it's another thing to have the vice president go to Langley and pressure people," he said, referring to former Vice President Dick Cheney's repeated visits to C.I.A. headquarters before the Iraq war.