The two main reasons for invading Afghanistan was to ramp up and control the opium production and get heroin addiction rising, they were successful.

The other reason was so that they could build an oil pipeline to move oil from Azerbaijan and Central Asia through Afghanistan and on to Pakistan and India, they were again successful.

The US invaded on 10/7/2001 - less than 4 weeks after the 9/11 attack. The US already had it's warships in the region and it's supply lines, logistics and battle plans drawn up long before 9/11.

The US ordered the Taliban to hand over bin Laden and expel al-Qaeda. The Taliban said that they would extradite bin Laden but asked to see evidence of his involvement in 9/11. The US refused to supply the evidence because they didn't have any so they just invaded instead and most of the world applauded them for doing so.

Then they turned to Iraq, today it is on Syria and tomorrow it will be Iran.