It was done immediately after Silverstein took ownership and an insurance policy. The Israelis used to to pull USA into the middle east to fight their battles. As well as make some insiders very wealthy. The idea may have been decades old, but the buildings were wired in the weeks leading up to 9/11. You cant wire a building for demo when you build it and just leave the charges in there.

Silverstien had plans for a new building 7 but couldnt get a demo permit. Cant implode buildings in NYC. They new about aesbestos towers and a billion dollar cost to fix it, so they knocked them all down in an insurance fraud scam. Everyone wins except muslims and regular americans.