The documents also showed that Osama was very much in-charge of al-Qaeda and remained a key decision maker till he was killed in the 2011 Navy SEALs raid in Pakistan's garrison city of Abbottabad.
The papers were released at the Brooklyn Federal court terror trial of Abid Naseer, a 28-year-old Pakistani who is accused of plotting to launch an attack on the New York subway system.
"Sheikh Yunis is ready to move and travel. The destination, in principle, is Iran, and he has with him 6 to 8 brothers that he chose. I told him we are waiting for final complete confirmation from you to move, and agree on this destination (Iran)," the unnamed top al-Qaeda operative said.
"His plan is: stay around three months in Iran to train the brothers there then start moving them and distributing them in the world for their missions and specialities. He explained those to you in his report and plan," the operative wrote.
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Other intelligence recovered in the raid on the then al-Qaeda chief's home show that al-Qaeda and Iran were at odds in some ways. Iran detained a number of senior al-Qaeda leaders and members of Osama's family.
Al-Qaeda forced Iran to release some of them by kidnapping an Iranian diplomat in Pakistan.
Also, a June 2010 memo to Osama indicates that al-Qaeda had a significant presence in Afghanistan at the time.
"Our groups inside Afghanistan are the same as for every season for many years now," Osama's subordinate wrote.
In the operation to capture Osaman and bring him to justice, US commandos recovered a treasure trove of material from his hideout where they were able to evaluate some of his ongoing communications and even some of his thinking about the state of al-Qaeda.