More seriously, it can only be the absolute arrogance of the US empire and its representatives that prevented them from seeing this coming from a mile away. When 9/11 happened back in 2001 the Taliban had already offered to turn over Osama bin Laden for trial - a pledge they repeated after the attacks on New York and Washington. But Bush was determined to wage a war to restore America's honour and the fear-effect - basically sending the message that if you mess with America you will pay the ultimate price. But to wage the War on Terror required regional allies - for resupplying troops, air fields, etc - to strategic and logistical access to land-locked Afghanistan. Problem was that the Taliban were proxies for Pakistan as part of its desire to limit the influence of India upon Pakistan's neighbours. There was also a deep element of Islamism inside Pakistan's ISI (not dissimilar to the Christian fundamentalism at the top of the US military, actually). All of this was well known by anyone who had done any research on the region as presumably the president's military and national security advisors would have done. At the time Pakistan was being governed by a military dictatorship under General Musharraf, which was trying to reduce the power of the Islamists and make the deeply corrupt Pakistani political system less dysfunctional. It was also open to US bribery to turn their backs on the Taliban.
But the US wasn't happy with just overthrowing the Taliban and weren't interested in dealing sensitively with the complex and precarious situation within Pakistan. They were on a crusading mission to crush not just the Taliban but Talibanism - the ideology (which they had helped to create, along with the Saudis, during the war against Soviet involvement in Afghanistan). To do that required crossing the arbitrary and porous Pakistani border into the Pashtun tribal areas where links with Afghanistan were still strong. This unrelenting disrespect for Pakistani sovereignty helped to bring down Musharraf and has kept the present kleptocratic regime in a state of permanent instability. The US - and to some extent Pakistan - may have been able to kill hundreds of guerillas but their actions have helped to create thousands more. And it has made the Islamist elements in the ISI more, not less, amenable to US power in the region. With each insult to Pakistani sovereignty the hostile elements within the ISI - perhaps the whole leadership - have become more emboldened to help the people America was attacking. After all, these guerillas were Pakistanis, fighting for Pakistani honour and would strengthen Pakistan's strategic interests in Afghanistan where Afghan President Hamid Karzai has long made clear his own hostility to Pakistan's role in his country.
All of which brings us back to the US now openly acknowledging that their former high priced partner in the war on terror is, in fact, using American aid to attack American interests. Oops. That's as embarrassing as your girlfriend driving the car you bought her for her birthday through your livingroom window. Only, in this case, the car also had a bomb in it. America - and its allies, like Canada - have only themselves to blame for this debacle. Ten years after going into Afghanistan to extend the power of the American empire into the post-Soviet imperial vacuum, they are weaker, more beleaguered, and have less regional influence than ever before. With the active hostility of Pakistan America and NATO can only lose in Afghanistan. The results of that growing hostility are now on clear display - the attack on the US embassy, the assassination of the chief peace negotiator, former Afghan president Berhanuddin Rabbani. The head of the CIA may try to pretend that these two bold attacks were "a sign of the Taliban's weakness" but it's not likely that anybody besides Fox News will believe him. The NATO intervention can no longer even keep key Afghan government officials safe. Not a great record after ten years of "successes".