Reading Abdul Salam Zaeef: My Life with the Taliban:

Even though Pakistan and the ISI maintained close relations with the Taliban, they also continued to uphold their ties to our opposition.

Both before and after 11 September 2001, they assisted various commanders who were operating against us, giving them permission to carry weapons and organize themselves politically. Some of the commanders —like Karzai, Abdul Haq,2 Mullah Malang3 and Gul Agha Shirzai— were in direct contact with America and were working with the CIA and FBI. They received financial and other assistance through the US embassy. They enjoyed a considerable freedom and privileges in Pakistan. They were—and some still are—important commanders, but without the support of the US they would have had little influence.

A former leading mujahed lived on Street F-10–3, where our own embassy guesthouse was also located. We watched his activities closely from the embassy, and set up surveillance equipment to record the phone calls coming in and out; we also tracked the movements of his associates. There was constant activity at his house, and every two or three days men from the ISI would pay him a visit. At times, even other opposition leaders would gather there. He used to meet Hezb-e Islami commanders and exchange views with the Northern Alliance, the main opposition to the Taliban, led by Ahmad Shah Massoud. From this surveillance we learned that money was being passed to support the Northern Alliance.