Authorities believe that the attack could not have taken place without the prior knowledge and assistance of the Haqqanis, the powerful Taliban group thought to be shielding bin Laden.
The attack was carried out by a Jordanian doctor whom the CIA believed was about to divulge the whereabouts of bin Laden's deputy, Ayman al-Zawahiri.
It is one of the deadliest blows against the CIA and has increased tensions between the U.S. and Pakistan because of Islamabad’s repeated failure to target the Haqqanis.
The Haqqanis control a large block of territory on both sides of the Afghan-Pakistan border near the Afghan town of Khost, a Taliban hotbed near where the CIA officials were killed on December 30. It is also where the U.S. believes bin Laden is hiding.
One former CIA officer, who did not wish to be named, told The Times of London that the agency had taped evidence of a Pakistani army officer tipping the Haqqanis off about a raid and a member of Pakistan's intelligence service boasting that the "Haqqanis are our guys."
Pakistan has ignored U.S. demands to target the strongholds of the Haqqanis’ leader, Sirajuddin Haqqani, whose father, Jalaluddin, founded the network and was a Mujahidin commander and ally of the U.S. during the Soviet occupation of Afghanistan in the 1980s. The network is said to be behind several audacious attacks, including the bombing of the Indian embassy in Kabul in July 2008.