I do believe the impacts were able to weaken the fire protection on the steel beams, and the hour+ of burning jet fuel enough to make those steel beams soft enough that the weight of the building above was enough to snap them. I don't believe there were any explosive charges at all.

That said, I do now believe at least John Brennan and several FBI people (Mueller probably included) knew at least a little bit of the plot, enough to approve those visas (Brennan) and ignore all the warning signs (pilot school reports to the FBI).