What country flew an airplane into any U.S. building? Terrorist group of Saudis, who were former apid CIA agents in Soviet-Afghanistan war, did that. Maybe our CIA should cut that kind of shit out, eh?
Then you bring up WMD, Saddam had no working WMD nor WMD program when US invaded. What he did have were long-expired weapons with UN tags on them, that were built with dual-use tech and billions of dollars given to him by ...wait for it..the United States of America. Because at the time he was our bestest pal, even made an honorary citizen of Detroit by the mayor for his donations to church, etc.
I'd second the SA blame for 911, but even more directly responsible than them would have to be Pakistan.
The American support for the mujahideen during the Soviet-Afghan times wasn't solely to Al Qaida chaps, but to anyone willing to fight the Russians, including Al Qaida and the Taliban and the Afghan Northern Alliance folks that were their enemies. It's not lying per se to claim that America supported people that would later become key players in the Taliban and Al Qaida, but it's certainly less than half of the truth.
Pakistan however had continued to support the Taliban right on through. Part of Pakistan's war planning against India was 'strategic depth' into Afghanistan where the friendly and allied Taliban forces gave room for them to move into and operate alongside. The Taliban being as largely uneducated and prone to fanatacism as they were made Al Qaida a moderate voice for Pakistan to work with the Taliban through as well. Pakistan's ISI(equivalent of the CIA) was deeply, deeply in bed with the Taliban and Al Qaida. When the towers went down, the American response was who could have or might have done this? The immediate response in tribal Pakistan was different and two fold. First, shock that Bin Laden actually went through with it and actually did it. The second, was when the Americans go to war with the Taliban, whose side will Pakistan take, and bets where 50/50.
Make no mistake, the Afghan war was 100% about Pakistan's response and ensuring that it and it's nuclear arsenal took sides against jihadists and severed it's buddy, buddy relationship with them. It was never stated outright publicly though, because that would be impolite and push Pakistan to refusing on principal, which it very nearly did anyways.