Patrick Cockburn, long-time war correspondent in Iraq and Afghanistan, writes a long piece on Afghanistan:
There was a fecklessness about the whole venture on the American and British side. Not surprisingly other Nato allies wondered what exactly they were getting into in sending their troops to Afghanistan. Comparisons with Iraq can be misleading but intervention in both countries never had overwhelming or even majority political support at home. Casualties were not particularly heavy compared to many other wars, but Iraqi or Afghan guerrillas are able to inflict casualties which are politically unsustainable for the American or British governments.
The main US ally in its war on terror was going to be Pakistan under General Pervez Musharraf, though it was an open secret that it was the Pakistani intelligence agency, the ISI, which had fostered the Taliban and established it in power in Kabul. So long as it had the covert backing of the ISI, the Taliban was never going to be truly defeated. "A year after 9/11 it was clear to many Pakistanis," writes Ahmed Rashid in his book Descent Into Chaos, "that Musharraf's support of the US-led war in Afghanistan was not the promised strategic U-turn that would end the army's long-standing support for Islamic extremists but rather a short-term tactical move to appease the United States and off-set India's hegemony." The reality on the ground was that the Taliban was the foster-child of the ISI. General Musharraf was prepared to join in an unenergetic pursuit of Arab members of al-Qa'ida in Pakistan. But the main objectives of the Pakistani army's traditional policy were never abandoned. These were to resist India, support the Muslims of Kashmir, protect the Pakistani nuclear arsenal and seek to establish a pro-Pakistani government in Kabul.
From the beginning, the army saw Afghan President Hamid Karzai's government as an enemy of Pakistan. Once the US decided to invade Iraq in 2003 General Musharraf concluded Washington was none too serious about its war on terror and the Taliban could be quietly revived. By 2006 the insurgency was back in business.