Because the Taliban government under Mullah Omar refused to hand over Osman Bin Laden to the United States to stand trial for alleged involvement in the attack on the Twin Towers. They did agree to hand him over to a neutral country were he could stand trial but the US and Britain said that was unacceptable. Then soon after the rejection Mullah Omar claimed that the Afghan government had no idea where Osman Bin Laden was, this was deemed unacceptable by the US and Britain who had assured Mullah Omar that Afghanistan would not be attacked if they handed over Bin Laden, so Afghanistan was attacked through air strikes. This allowed the Northern Alliance led by warlords and which only controlled only a very small enclave inside Afghanistan (where 90% of opium production occurred) to seize power. Unable to effectively maintain control of Afghanistan, NATO committed ground troops to help the Northern Alliance. Very soon all attempts to find Osman Bin Laden and arrest him so that he could stand trial were forgotten, and the objective completely changed to one in which the overriding priority became to stop the Taliban regaining power. NATO are still in Afghanistan to “train” the Afghan army, apparently Afghans are rubbish when it comes to fighting wars and even after over 10 years we haven’t finished training them. Although I suspect the real reason we’re still there is that the Afghan government and army can’t be trusted to do what we tell them unless we are there to make certain they do. We are also busy negotiating with the Taliban – apparently they are not as bad as we first thought. Shame we didn’t realise that negotiating with the Taliban was an option over 10 years ago before we went to war.
Interestingly as far back as 1998 the Taliban were apparently considering handing over Bin Laden to the US, but this was scuppered by the US government’s cack-handed behaviour :
Taliban agreed Bin Laden handover in 1998
“The Taliban leader, Mullah Mohammed Omar agreed three years ago to hand over Osama bin Laden, but changed his mind after US cruise missile attacks, the former head of Saudi Arabian intelligence said yesterday.
The claim, by Prince Turki al-Faisal, is likely to raise questions about whether more efforts could have been made to negotiate Bin Laden’s extradition before launching the latest bombing campaign.”
I’m sure the fact that the original objective of the attack on Afghanistan, ie to arrest Osman Bin Laden and put on trial, was so quickly and completely forgotten, was the reason why Tony Blair was so confident that he could use disarming Iraq of WMDs as an excuse for attacking Iraq. He undoubtedly assumed that very quickly people would forget why we had attacked and invaded Iraq. Unfortunately for Blair whilst people six months on weren’t asking “so where’s Osman Bin Laden ? why haven’t we arrested him?”, they did in the case of Iraq ask “so where’s these WMDs then ?”. He was extremely unlucky on that score.