James Risen / New York Times News Service

WASHINGTON — At the nation’s top spy agency, the ghosts of Iraq are never far away.

One CIA 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 CIA 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 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 Thielmann, now a senior fellow at the Arms Control Association in Washington.

Paul Pillar, a former senior CIA 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 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 U.S. 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 CIA 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.