Pakistan's tribal areas, where Osama bin Laden found refuge, were momentarily open to its army when "the tribes were overawed by US firepower" after 9/11, but quickly again became "go" areas where Taliban could reorganize and plan their resurgence in Afghanistan, some of the declassified US documents have revealed.
The documents, of the events following the immediate aftermath of 9/11, were released by the National Security Archive of the George Washington University.
US Ambassador to Afghanistan, Ronald E Neumann, said the 2005 Taliban resurgence in Afghanistan was a direct product of the "four years that the Taliban has had to reorganise and think about their approach in a sanctuary beyond the reach of either government."
This had exponentially increased casualties as the Taliban adopted insurgency tactics in Iraq, including suicide bombings and the use of Improvised Explosive Devices (IEDs).
Neumann warned Washington if the sanctuary in Pakistan were not addressed it would "lead to the re-emergence of the same strategic threat to the US that prompted our OEF (Operation Enduring Freedom) intervention" in 2001.
"I believe that what we are seeing is largely the result of four years that Taliban has had to reorganize and think about their approach in a sanctuary beyond the reach of either Government," he wrote in a secret cable to Washington.
"This will lead to the increasing violence this summer; it will lead to a long-term continuation of the insurgency as long as they can resupply from their current areas; and, if left unaddressed, it will also lead, to the re-emergence of the same strategic threat to the US that prompted our OEF intervention over 4 years ago," he warned.
Another classified document, released on Tuesday, which was meant as a policy paper for the then US Vice-President, refutes the claims made by Pakistani officials that there is no terrorist safe haven in their country, The Issue Paper observes "some Taliban leaders operate with relative impunity in some Pakistani cities, and may still enjoy support from the lower echelons of Pakistan's ISI."
But the "insurgency is not monolithic." Various insurgent groups such as the Taliban, al-Qaeda, Hizb-i-Islami Gulbuddin (HiG) members, Haqqani and Jaish-i- Muslimeen have "varying agendas, and lack internal cohesion," it said.
The paper describes Kabul's strategy for combating the insurgency as focusing "first on military action, second on the Taliban reconciliation process and third, improving relations and security cooperation with Pakistan."
The document also discusses non-military means of combating the Taliban as the State Department concludes "the Afghan Government's program to reconcile lower and mid-level Taliban fighters has been moderately effective, but not yet realised its potential.