(CNN) -- Pakistan's intelligence agency, the ISI, calls the shots for the Taliban and other insurgent groups in Afghanistan, training, funding and giving shelter to them, a Harvard academic claims in a new paper.
The powerful ISI does not "actually control the Afghan insurgency" and does not have "the ability to bring it to an end," Matt Waldman argues in a paper for the London School of Economics.
But it provides "sanctuary, and very substantial financial, military and logistical support to the insurgency," giving it "strong strategic and operational influence -- reinforced by coercion," the paper says.
The ISI works not only with the Taliban, but also with the armed Haqqani network led by former government ally Gulbeddin Hekmatyar, which sometimes cooperates with the Taliban and sometimes fights it, according to the paper.
Waldman bases his conclusions on interviews he conducted with nine insurgent field commanders in three regions of Afghanistan, plus former Taliban officials, tribal leaders, politicians, experts and diplomats.
Pakistan's ISI is widely thought to have played a key role in creating the Afghan Taliban but Pakistan officially denies supporting them now.
Islamabad did not immediately respond to Waldman's report, "The Sun in the Sky: The relationship between Pakistan's ISI and Afghan insurgents".
Its title comes from Taliban commanders' claims that their relationship with Pakistani intelligence is "as clear as the sun in the sky".
