Ah, but Iran did have a hand in 9/11. There's a long trail of proof and a judge ruled, as well (link to case website with lots of info is below quotes from this first article).
Remember Iran’s Role in 9/11
by Sen. Joe Lieberman (now retired)
http://www.wsj.com/articles/remember-irans-role-in-9-11-1473290470
“there is strong evidence that Iran facilitated the transit of al Qaeda members into and out of Afghanistan before 9/11, and that some of these were future 9/11 hijackers. ...”
"Iran’s link to al Qaeda goes back to Sudan in the early 1990s ..."
"the Washington Institute’s Matthew Levitt and Michael Jacobson concluded, “Iran and al-Qaeda reached an informal agreement to cooperate, with Iran providing critical explosives, intelligence, and security training to bin Laden’s organization.” Because Islamic Revolutionary Guard Corps (IRGC) already supported Hezbollah operationally and financially, a vehicle was in place through which they could support and influence al Qaeda. ..."
"Operating through Hezbollah gave Iran immense freedom to funnel money and weaponry and to train al Qaeda operatives in deadly tactics that would be employed around the world, including against the U.S. ..."
"After 9/11, Iran became a more important haven for al Qaeda fighters who fled from Afghanistan as the Taliban collapsed. Iran claimed that these terrorists were under “house arrest. ...”
In reality, Iran regularly granted the terrorists freedom to move within Iran and to cross into Iraq and Afghanistan to carry out attacks. From their safe base in Iran, al Qaeda members planned terrorist operations ..."
"It took the U.S. government 10 years to publicly acknowledge Iran’s aid to al Qaeda. In 2011, the Treasury Department officially accused Iran, as a Wall Street Journal report put it, “of forging an alliance with al Qaeda in a pact that allows the terrorist group to use Iranian soil as a transit point for moving money, arms and fighters to its bases in Pakistan and Afghanistan. ...”
"As recently as July 20, 2016, the U.S. blacklisted three members of al Qaeda who were living in Iran, saying these al Qaeda facilitators in Iran had helped the jihadist group on the battlefield, with finance and logistics, and in liaising with Iranian authorities. Newly declassified letters captured in the May 2011 raid that killed Osama bin Laden reveal how crucial Iran has been to al Qaeda. In a 2007 letter, bin Laden directed al Qaeda not to target Iran because “Iran is our main artery for funds, personnel, and communication. ...”
U.S. DISTRICT COURT RULES IRAN BEHIND 9/11 ATTACKS
http://www.iran911case.com/