Yes, four guys who only need to know how to fly a jet. Not land it. All the rest were for crowd control. They probably were not even told they were going to crash the planes. Most likely they were told they were going to hijack only. They did billions in damage to the US economy. They were armed with box cutters.
One of Clancy’s last book had a terrorist attack on the US at a shopping mall. Four or five guys came up through the Mexican border. They shot up a mall in the mid west with semi automatic weapons. The attack was planned for the weekend prior to Thanksgiving to scare people enough to stay home on Black Friday.
This type of attack would not have nearly the same effect today unless they took down Amazon’s and Walmart’s servers so nobody could buy online.
William Forstchen who wrote the book, “One Second After”, has another book that’s around 200 pages of a series of ISIS attacks on elementary schools at multiple locations around the country, even though its fiction is gives everyone an idea of the damage a few determined terrorists with a well thought plan can do.