Apparently Hasan has been following the news from the Middle East and has been impressed by the conquests of the Islamic State Army (also known as ISIS or ISIL). The Islamic State has conquered big hunks of Iraq and Syria and has been massacring people right and left. Hasan was impressed enough to write the group´s leader and request citizenship. Sounds like Hasan would fit right in.
Nidal Hasan, the convicted shooter in the Fort Hood attack that left 13 dead and more than 30 injured, has written a letter to the head of the Islamic State, requesting to become a “citizen” of the terrorist organization. .
“I formally and humbly request to be made a citizen of the Islamic State,” Hasan wrote in the letter to “Ameer, Mujahad Dr. Abu Bakr al-Baghadadi,” Fox News reported. “It would be an honor for any believer to be an obedient citizen soldier to a people and its leader who don’t compromise the religion of All-Mighty Allah to get along with the disbelievers.”
Hasan signs his letter with his name and the abbreviation SoA — Soldier of Allah.
John Galligan, the attorney for Hasan, said the letter “underscores how much of his life, actions and mental thought process are driven by religious zeal. And it also reinforces my belief that the military judge committed reversible error by prohibiting Major Hasan from both testifying and arguing … how his religious beliefs” motivate his shooting,” Fox News reported. Fort Hood shooter Nidal Hasan petitions to be 'citizen' of Islamic State (Washington Times, Aug. 29, 2014)
Here's my article on the Hasan shooting, published a few days after it occurred: Remembering Fort Hood - How The Massacre Happened.