"The namechecks are still pending, but we believe a significant percentage are intelligence officers," the cable noted.

Iran, with its suspected nuclear weapons program, ties to terrorist groups, and attempts to spread influence throughout the Middle East, has been a prime foreign policy headache for both the George W. Bush and Obama administrations.

But the 295 "Iran watcher" reports reviewed by McClatchy, out of 251,287 cables obtained by WikiLeaks, also show what seem to be missed chances at reconciliation between the adversaries.

In November 2008 and again in April 2009, U.N. officials and a former Iranian official told U.S. diplomats in Istanbul, Turkey, that the Tehran regime would welcome an American offer of counter-narcotics cooperation. Iran is plagued with rampant drug addiction and opium trafficked from neighboring Afghanistan.

But Washington apparently never picked up on the proposal.

In a more humorous encounter, a U.S. official found herself staying in the same hotel, on the same floor, as Iranian President Mahmoud Ahmadinejad during the latter's August 2008 visit to Istanbul.

A cable relates what happened next: "She was approached in the lobby by an Iranian official mistaking the (U.S.) official for a Western reporter and asking her if she had any question to ask him."

The Iran watcher program is relatively small, current and former U.S. officials say, comprising about 15 diplomats stationed in Azerbaijan, Turkey, Turkmenistan, Afghanistan, Iraq, Great Britain, Germany and Dubai, in the United Arab Emirates. Its unofficial headquarters is the State Department's Iran Regional Presence Office in Dubai, where an estimated 700,000 Iranians live.

A State Department official in Washington said the program was established in 2006 for three reasons: to improve U.S. knowledge about Iran; to prepare a cadre of diplomats should the United States ever re-establish a diplomatic presence in Tehran; and to build up a corps of Farsi-language speakers.

Before the program, the number of State Department Farsi-speakers with knowledge of Iran "was three, maybe four," said the official, who was not authorized to speak for the record.

While many of the contacts outlined in the cables come from Iranians seeking visas or even pro-democracy assistance from U.S. contacts, they also portray American diplomats making creative efforts to engage with a broader slice of Iranians.

In early 2010, a U.S. diplomat based in Turkmenistan's capital of Ashgabat, traveled to the nearby border with Iran to talk to Iranian truck drivers crossing the border.

Some of those truckers predicted, erroneously, that Ahmadinejad would be forced out within a year. Others complained that President Barack Obama had not kept his promise to close the Guantanamo Bay detention facility.

Whatever their reliability, such efforts provide "a real reality check" to talking only to elite, educated Iranians who travel abroad, said a U.S. official, who asked not to be identified because he wasn't authorized to talk for the record.

Iran seems well aware of the U.S. effort, which the regime no doubt considers little short of espionage.