Khan was known to be a conservative Muslim. At army staff college, he had the nickname "Mullah Rocketi" — roughly "rocket cleric" — and was lampooned in a graduation skit as a cleric, said one of his colleagues.
At the same time, anti-Americanism has been rising, fueled by anger at U.S drone strikes in the tribal regions, the killing of two Pakistanis by a CIA contractor in 2011 and the U.S. border post attack in November.
Some soldiers and officers have carried out occasional, but serious, terrorist attacks against the institution they once served. Militant sieges against army headquarters in Rawalpindi in 2009 and against a navy base in Karachi weeks after the bin Laden raid are both alleged to have had inside help.
The 600,000-member army releases little data on its enrollment or makeup, so its hard to say whether it is undergoing Islamization. A study last year on what limited data found no evidence the force was recruiting disproportionately from conservative areas of the country.
Image: A member of the Pakistani navy stands guard outside the Pakistan's Mehran naval air base in Karachi on May 24, 2011. A siege on the major naval base in the heart of Pakistan's biggest city that took 17 hours to quell heaps humiliation on a military still reeling from the fallout over Osama bin Laden, experts say.