When the State Department recently asked the CIA for names of Iranians who could be sanctioned for their involvement in a clandestine nuclear weapons program, the agency refused, citing a large workload and a desire to protect its sources and tradecraft.

Frustrated, the State Department assigned a junior Foreign Service officer to find the names another way -- by using Google. Those with the most hits under search terms such as "Iran and nuclear," three officials said, became targets for international rebuke Friday when a sanctions resolution circulated at the United Nations.

Policymakers and intelligence officials have always struggled when it comes to deciding how and when to disclose secret information, such as names of Iranians with suspected ties to nuclear weapons. In some internal debates, policymakers win out and intelligence is made public to further political or diplomatic goals. In other cases, such as this one, the intelligence community successfully argues that protecting information outweighs the desires of some to share it with the world.

But that argument can also put the U.S. government in the awkward position of relying, in part, on an Internet search to select targets for international sanctions.

None of the 12 Iranians that the State Department eventually singled out for potential bans on international travel and business dealings is believed by the CIA to be directly connected to Iran's most suspicious nuclear activities.

"There is nothing that proves involvement in a clandestine weapons program, and there is very little out there at all that even connects people to a clandestine weapons program," said one official familiar with the intelligence on Iran. Like others interviewed for this story, the official insisted on anonymity when discussing the use of intelligence.

What little information there is has been guarded at CIA headquarters. The agency declined to discuss the case in detail, but a senior intelligence official said: "There were several factors that made it a complicated and time-consuming request, not the least of which were well-founded concerns" about revealing the way the CIA gathers intelligence on Iran.

That may be why the junior State Department officer, who has been with the nonproliferation bureau for only a few months, was put in front of a computer.

An initial Internet search yielded over 100 names, including dozens of Iranian diplomats who have publicly defended their country's efforts as intended to produce energy, not bombs, the sources said. The list also included names of Iranians who have spoken with U.N. inspectors or have traveled to Vienna to attend International Atomic Energy Agency meetings about Iran.

It was submitted to the CIA for approval but the agency refused to look up such a large number of people, according to three government sources. Too time-consuming, the intelligence community said, for the CIA's Iran desk staff of 140 people. The list would need to be pared down. So the State Department cut the list in half and resubmitted the names.

In the end, the CIA approved a handful of individuals, though none is believed connected to Project 1-11 -- Iran's secret military effort to design a weapons system capable of carrying a nuclear warhead. The names of Project 1-11 staff members have never been released by any government and doing so may have raised questions that the CIA was not willing or fully able to answer. But the agency had no qualms about approving names already publicly available on the Internet.

"Using a piece of intel on project 1-11, which we couldn't justify in open-source reporting, or with whatever the Russians had, would have put us in a difficult position," an intelligence official said. "Inevitably, someone would have asked, 'Why this guy?' and then we would have been back to the old problem of justifying intelligence."