Plans to bring down the Towers first began under GHWB. However, the STEM of building implosion/demolition wasn't quite as well understood in the early 90's. Blowing up a truck bomb in the twin towers would have been a great way to gather data on how force, energy, and waves travel thru the same structure. And, since they're going thru the effort of blowing up one of their own federal buildings in OKC, might as well take the time and put in some extra monitoring equipment. There might be evidence of such equip in some of the photos from either site. Researching the evolution of the tech related to building demolition might give some clues as to who would be in on such a thing from the academic side. Almost certainly Israelli or significantly connected to Israel somehow.