Many think you are mistaken. From britannica.com:
In 1996 the Taliban seized Kabul and instituted a severe interpretation of Islamic law that, for example, forbade female education and prescribed the severing of hands, or even execution, as punishment for petty crimes. That same year, al-Qaeda leader Osama bin Laden was welcomed to Afghanistan (having been expelled from Sudan) and established his organization’s headquarters there. With al-Qaeda’s help, the Taliban won control of over 90 percent of Afghan territory by the summer of 2001. On September 9 of that year, al-Qaeda hit men carried out the assassination of famed mujahideen leader Ahmad Shah Masoud, who at the time was leading the Northern Alliance (a loose coalition of mujahideen militias that maintained control of a small section of northern Afghanistan) as it battled the Taliban and who had unsuccessfully sought greater U.S. backing for his efforts.
The September 11 attacks and the U.S.-British invasion
The hijacking and crashing of four U.S. jetliners on September 11, 2001, brought instant attention to Afghanistan. The plot had been hatched by al-Qaeda, and some of the 19 hijackers had trained in Afghanistan. In the aftermath of the attacks, the administration of U.S. Pres. George W. Bush coalesced around a strategy of first ousting the Taliban from Afghanistan and dismantling al-Qaeda, though others contemplated actions in Iraq, including long-standing plans for toppling Pres. Saddam Hussein. Bush demanded that Taliban leader Mullah Mohammed Omar “deliver to [the] United States authorities all the leaders of al-Qaeda who hide in your land,” and when Omar refused, U.S. officials began implementing a plan for war.
The Taliban took out Ahmad Shah Masoud just prior to the war we’re in.
In other words, no real connection and certainly nowhere near enough to justify 18 years of war.