The killing of Osama bin Laden deep inside Pakistan in an American operation, almost in plain sight in a medium-sized city that hosts numerous Pakistani forces, seems certain to inflame tensions between the two countries. It raises questions on whether ISI knew about the whereabouts of bin Laden.
The presence of bin Laden in Pakistan, something Pakistani officials have long dismissed, goes to the heart of the lack of trust Washington has felt over the last 10 years.
With bin Laden's death, perhaps the central reason for an alliance forged on the ashes of 9/11 has been removed. Currently, relations between the two countries are at one of their lowest points as their strategic interests diverge over the shape of a post-war Afghanistan.
For nearly a decade, the US has paid Pakistan over $1 billion a year for counterterrorism operations. The chief aim was to kill or capture of bin Laden.
The circumstances of bin Laden's death may not only jeopardize that aid, but will also no doubt deepen suspicions that Pakistan has played a double game, and perhaps even knowingly harboured him.
According to some reports, the compound and its elaborate walls and security gates may have been built specifically for bin Laden in 2005, hardly an obscure undertaking in a part of the city that the residents described as highly secure.
Al Qaeda operative, Umar Patek, an Indonesian involved in the Bali bombings in 2002, was captured at a house in Abbottabad in February, where he was protected by an al Qaeda courier, who worked as a clerk at the city post office.
Almost instantly, the death of bin Laden in such a place in Pakistan led to fresh recriminations from its neighbours.
"The fundamental challenge is how would the West treat Pakistan from now on?" said Amrullah Saleh, former intelligence director for Afghanistan and a fierce foe of Pakistan.
Still, it is too soon to say whether bin Laden's presence in Abbottabad reflected Pakistani complicity or incompetence.
The capture in Pakistan of other top operatives - Khalid Shaikh Mohammed and Abu Zubaydah - in the years immediately after 9/11 make it clear that Pakistan is easy to hide in. But those high-profile joint operations have declined in the last few years.
At the very least, bin Laden's death in Pakistan now will be highly embarrassing to the country's military and intelligence establishment.