Pakistan’s top military officials are worried about militant collaborators in their ranks

Those worries have grown especially acute since the killing of bin Laden less than a mile from a prestigious military academy. This week’s naval base infiltration by heavily armed insurgents in Karachi — an attack widely believed to have required inside help — has only deepened fears, military officials said.

Pakistan’s army chief, Gen. Ashfaq Kayani, who like the civilian government haspublicly expressed anger over the secret U.S. raid, was so shaken by the discovery of bin Laden that he told U.S. officials in a recent meeting that his first priority was “bringing our house in order,” according to a senior Pakistani intelligence official, citing personal conversations with Kayani.

“We are under attack, and the attackers are getting highly confidential information about their targets,” said the official, who, like others, would speak only on the condition of anonymity to discuss a sensitive matter.

Pakistan’s top military brass claimed to have purged the ranks of Islamists shortly after the Sept. 11, 2001, attacks. Since then, the nation’s top officials have made repeated public assurances that the armed forces are committed to the fight against extremists and that Pakistan’s extensive nuclear arsenal is in safe hands.

But U.S. officials have remained unconvinced, and they have repeatedly pressed for a more rigorous campaign by Pakistan to remove elements of the military and intelligence services that are believed to cooperate with militant groups.

U.S. Secretary of State Hillary Rodham Clinton, on a previously unannounced visit to Islamabad on Friday, emphasized U.S. demands for greater cooperation in the war against al-Qaeda, the Taliban and other violent Islamist organizations that have taken root in Pakistan. Standing beside Adm. Mike Mullen, chairman of the Joint Chiefs of Staff, Clinton said the United States would be looking “to the government of Pakistan to take decisive steps in the days ahead.”

It is unclear how authentically committed Kayani and other top military leaders are to cleansing their ranks. U.S. officials and Pakistani analysts say support by the nation’s top military spy agency for insurgent groups, particularly those that attack in India and Afghanistan, is de facto security policy in Pakistan, not a matter of a few rogue elements.

But Kayani is under profound pressure, both from a domestic population fed up with the constant insurgent attacks and from critics in the U.S. government, who view the bin Laden hideout as the strongest evidence yet that Pakistan is playing a double game.

U.S. officials say they have no evidence that top Pakistani military or civilian leaders knew about bin Laden’s redoubt, though they are still examining intelligence gathered during the raid. Some say they doubt Kayani or Lt. Gen. Ahmed Shuja Pasha, head of the military’s Inter-Services Intelligence agency, had direct knowledge; others find it hard to believe they did not, particularly because Kayani was head of the ISI in 2005, when bin Laden is believed to have taken refuge in Abbottabad.