U.S. faces a tricky task in assessing data on Iran

Washington — While U. S. spy agencies have believed that the Iranians halted efforts to build a nuclear bomb back in 2003, the difficulty in assessing the government’s ambitions was evident two years ago, when what appeared to be alarming newintelligence emerged, according to current and former U.S. officials.

Intercepted communications of Iranian officials discussing their nuclear program raised concerns that the country’s leaders had decided to revive efforts to develop a weapon, intelligence officials said.

That, along with a stream of other information, set off an intensive review and delayed publication of the 2010 National Intelligence Estimate, a classified report reflecting the consensus of analysts from 16 agencies. But in the end, they deemed the intercepts and other evidence unpersuasive, and they stuck to their longstanding conclusion.

The intelligence crisis that erupted in 2010, which has not been previously disclosed, only underscores how central that assessment has become to matters of war and peace.

Today, as suspicions about Iran’s nuclear ambitions have provoked tough sanctions and threats of military confrontation, top administration officials have said that Iran still has not decided to pursue a weapon, reflecting the intelligence community’s secret analysis. But if that assessment changes, it could lift a brake set by President Barack Obama, who has not ruled out military options as a last resort to prevent Iran gaining nuclear arms.

Publicly and privately, U.S. intelligence officials express confidence in the spy agencies’ assertions. Still, some acknowledge significant intelligence gaps in understanding the intentions of Iran’s leaders and whether they would approve the crucial steps toward engineering a bomb, the most covert aspect of one of the most difficult intelligence collection targets in the world.

Much of what analysts sift through are shards of information that are ambiguous or incomplete, sometimes not up to date, and that typically offer more insight about what the Iranians are not doing than evidence of exactly what they are up to.

As a result, officials caution that they cannot offer certainty. “I’d say that I have about 75 percent confidence in the assessment that they haven’t restarted the program,” said one former senior intelligence official.