Yeah, let's roll with the idea that the only building that gets damaged is the Pentagon and only partially. Let's say 506 people are dead total from TTL's version of 9/11. What do you feel the public response would be?
America is very, very pissed. But what tempers things is that only one building is hit, and it isn't as utterly shocking as two of the tallest buildings in the world both being hit and collapsing (in addition to the Pentagon), with huge collateral damage, and thousands dead. Would there be images as iconic as the second plane hitting the South Tower, people jumping to their inevitable deaths, scenes of firefighters rushing into the disaster, the collapse of those huge skyscrapers in general and the resulting cloud of dust?
Now, it's an event which will resonate in the American public for years, but I don't think it will have
as big of a shock as OTL 9/11. But unfortunately for al-Qaeda, the Taliban, and anyone who looked at America funny like Saddam Hussein, the Pentagon is a Department of Defense building, and the military and people like Donald Rumsfeld will be especially angry.