By disenfranchising the Majority Pashtuns. America Sowed the Seeds of a Popular Revolt in Afghanistan
When the United States decided to invade Afghanistan in October 2001 following the Al Qaida sponsored 9/11 attack on its soil, it was an American war being waged against the Taliban regime which was harbouring Al Qaida. Until then Al Qaida targets of terror attacks were focused primarily on America and its interests worldwide.
Other western states got drawn in the conflict when their forces under the umbrella of Nato became a part of the offensive. Pakistan became an unwilling coalition partner as it found itself caught in a severe bind because the only viable access to Afghanistan for the US military juggernaut was through its air and land spaces.
US demand for access was allegedly conveyed by the US president to his Pakistani counterpart in the following blunt words, "Either you are with us or against us, and if you are against us, be prepared to be bombed to the stone ages." Pakistan had little option but to concede to the US ultimatum, and was sucked into somebody else's long drawn war which it could ill afford...