In the rigid enemy-or-ally world view of Osama bin Laden and his chief lieutenants, Iran occupied a spot somewhere in between _ a state seen as arrogant, enigmatic and driven by self interest, according to newly released al-Qaida documents.
Yet there is also a sense that al-Qaida recognizes the importance of Iran's role in the region and the need to keep some level of dialogue.
The papers _ seized in last year's raid on bin Laden's Pakistan hide-out and posted online Thursday by the U.S. Army's Combating Terrorism Center _ portray al-Qaida's relations with Iran as clouded by deep mutual distrust and sharply divergent interests.
A June 2009 al-Qaida memo _ possibly to bin Laden _ refers to the Iranian government as "criminals" in a no-holds bashing of its opaque and unpredictable policies.
"The criminals did not send us any letter," wrote al-Qaida's top Afghanistan commander, Atiyah Abd al-Rahman, about the earlier kidnapping of an Iranian diplomat in Pakistan that was believed carried out by militants linked to al-Qaida.
"Such behavior is, of course, not unusual for (the Iranians); indeed it is typical of their mindset and methods," continued al-Rahman, who was killed the following year in a CIA drone strike in the Waziristan region of Pakistan. "They do not wish to appear to be negotiating with us or responding to our pressures."
In one narrow sense, al-Qaida and the West share this much: exasperation over Tehran's shifting and often contradictory messages that extend all the way to talks over its nuclear program.
The full extent of the interplay between Iran and al-Qaida remains unclear to Western policymakers. But the newly disclosed documents reinforce the long-held consensus that there is little common ground.
Al-Qaida operatives _ and even bin Laden relatives _ used Iran as an escape route during the U.S.-led military campaign in Afghanistan after the Sept. 11. attacks.
Iran was not willing to be an open passageway, however. Dozens of top al-Qaida figures, including one of bin Laden's sons, Omar, were placed under house arrest-style detention. Many were later released, but several high-ranking al-Qaida figures are believed to remain in Iran under close surveillance, including the network's most senior military strategist, Saif al-Adel, one of the alleged masterminds of the 1998 bombings of U.S. embassies in Africa.
In 2010, another of bin Laden's sons, Khalid, sent a letter to Iran's Supreme Leader Ayatollah Ali Khamenei claiming that his relatives were mistreated and "beaten and silenced." Al-Qaida's branch in North Africa issued a warning to Iran over the matter. Khalid was among those killed in the U.S. raid on bin Laden's compound in Pakistan a year ago.
The reasons behind the mutual suspicions cut across many of the region's main flashpoints.
Iran was a major foe of Afghanistan's Taliban, which sheltered al-Qaida before the Sept. 11 attacks and remains its close ally. In 1998, Sunni-led Taliban forces overran Mazar-e-Sharif in northern Afghanistan and were accused of killing eight Iranian diplomats as well as Afghans with cultural and religious ties to Iran, a Shiite power.
In Iraq, Sunni insurgents backed by al-Qaida often targeted Shiites in attempts to trigger an all-out civil war during the occupation by American forces.
Some hard-line militants backing al-Qaida _ which is made up almost entirely of Islam's majority Sunnis _ consider Islam's Shiite branch as heretical and view Iran's regional ambitions as a greater threat than the West. Last year, the al-Qaida faction in Yemen declared "holy war" against Shiite rebels that get apparent indirect support from Tehran.
Iran, meanwhile, is acutely aware of the consequences if it is perceived as accommodating toward al-Qaida. Key Iranian allies such as Russia and China tolerate Tehran's backing for anti-Israel militant groups led by Hamas and Hezbollah, but any major concessions to al-Qaida would risk crippling blows to Iran's strategic networks.
A possible motive for keeping the al-Qaida figures under Iranian custody is as insurance against possible retaliation attacks by the terror group. Also they could be used as bargaining chips with the West. In 2003, Iran received rare Western praise after giving the U.N. Security Council the names of 225 al-Qaida suspects detained after illegally crossing into Iran. The suspects were later deported to their countries in the Middle East, Europe and Africa.
The list included Yemen-born Naser Abdel Karim al-Wahishi, bin Laden's former private secretary, who was sent to his homeland and later escaped prison and helps lead the group al-Qaida in the Arabian Peninsula. Another, according to the newly released documents, was Salim al-Misri, who is believed to have received explosives training from Hezbollah.
The most direct contact between Iran and the al-Qaida leadership may have come during eventual negotiations in late 2009 to free the kidnapped diplomat, Heshmatollah Attarzadeh, who was held for nearly 15 months and released in March 2010.
Western officials believe that al-Qaida, in return for its help in freeing Attarzadeh, won the release of dozens of al-Qaida operatives and bin Laden family members, and better treatment for others remaining in Iranian custody.
In his June 2009 letter, the al-Qaida commander al-Rahman claimed the terror group outmaneuvered Iran's envoys during the talks over "their friend" Attarzadeh.
"Our efforts, which included escalating a political and media campaign, the threats we made, the kidnapping of their friend ... and other reasons that scared them," he wrote, "(were) among the reasons that led them to expedite" the release of the al-Qaida detainees.