this is cnn's special coverage. 20 years since the september 11th terror attacks. ceremony at the pentagon wrapping up. secretary lloyd austin will be joining me live in few minutes. we have lots to discuss on this important day. also, george w. bush and vice president kamala harris, they will speak live in shanksville, pennsylvania. all that coming up. right now, i want to bring in our pentagon correspondent, orin lieberman. i know this is an emotional day for the military men and women and the civilians who work here, as well. >> reporter: wolf, there were two incredibly difficult periods over the last few weeks leading up to this moment and this ceremony. first, on the day of the horrible terrorist attack at kabul international airport when 13 service members were killed. 11 marines, a sailor, and a soldier. that weighed on the building, that those would be the last