The Iranian military was so apprehensive about the threat of an Israeli airstrike on its nuclear installations in 2007 and 2008 that it mistakenly fired on civilian airliners and, in one instance, on one of its own military aircraft, according to classified American intelligence reports.
The civilian planes were fired on by surface-to-air missiles and antiaircraft batteries and intercepted by Iranian fighter jets.
"Iranian air defense units have taken inappropriate actions dozens of times, including firing antiaircraft artillery and scrambling aircraft against unidentified or misidentified targets," noted a heavily classified Pentagon intelligence report, which added that the Iranian military's communications were so inadequate and its training deficiencies so significant that "misidentification of aircraft will continue."
At the time, there was growing concern in Israel and the United States over Iran's nuclear program and discussion of a military response.
In September 2007, Israeli aircraft bombed a nuclear reactor that was under construction in northeast Syria. The following year, Israel conducted a major air exercise over the Mediterranean that appeared to be a rehearsal for a potential attack on Iran's uranium enrichment plant at Natanz.
In Iran, air defense units were edgy, fearing that an enemy aircraft might try to mimic the flight profile of a civilian airliner, according to a classified Pentagon assessment.
The combination of heightened vigilance and poor command and control led to series of mistakes, according to a highly classified 2008 Pentagon report on "Operational Mishaps by Air Defense Units."
In June 2007, the report noted, a Revolutionary Guards air defense unit fired a TOR-M1 surface-to-air missile at a civilian airliner. In May 2008, an antiaircraft battery fired on an Iranian reconnaissance drone and a civilian airliner. That same month, an antiaircraft battery fired on an Iranian F-14 fighter jet.
The report and other documents were examined for a new book.
In June 2008, soon after the Israeli air exercise, Iranian air defense units fired at two more civilian aircraft. In one instance, an Iranian F-4 fighter scrambled to intercept an Iraqi Airways flight from Baghdad to Tehran to visually inspect the passenger plane. The Iraqi Airways plane was not harmed.
The mishaps were not the first time that air defense forces fired at a civilian aircraft that was believed to be on a military mission. In September 1983, a Soviet pilot shot down a Korean 747 airliner that had strayed from its flight path to Seoul. The Soviet pilot later said in an interview that he knew that he was shooting at a civilian plane, but assumed that it was being used for a spy mission.
Worried about an Israeli strike, the Iranian military began to rehearse attacks of its own. Less than two weeks after Israeli warplanes practiced over the Mediterranean in June 2008, a classified Pentagon report noted, the commander of the Iranian Air Force ordered fighter units to "conduct daily air-to-ground attack training (GAT) at firing ranges resembling the Israeli city of Haifa and the Israeli nuclear facility at Dimona," according to a classified 2008 report by the Defense Intelligence Agency.
Iraqi officials had their own concerns about a possible Israeli strike. On July 3, 2008, Prime Minister Nuri Kamal al-Maliki of Iraq opened a videoconference with President George W. Bush by expressing his fear that Israel might fly through Iraqi skies to attack Iran.
If Israel violated Iraqi airspace, he said, he would have no choice but to hold the United States responsible, said Mr. Maliki, who said that he could not allow Iraq to "become a battleground."
"I hear you loud and clear," Mr. Bush assured Mr. Maliki, according to notes of the conversation. "Nothing is more important to me than success in Iraq."
This article originally appeared in The New York Times.