It was clearly established in National Swindle of the WTC that the FEMA, 9/11 Commission, and the NIST reports, all of which conclude that fires brought the WTC buildings down, are wrong and likely fraudulent. However, the question of how they came down was not fully answered in that book.
Despite the problem that much of the large amount of evidence in the destruction at and surrounding the WTC site was quickly removed and destroyed, enough was gathered to provide solid evidence that nano-thermite explosive was in all 3 collapsed buildings at the WTC. A detailed timeline of that evidence showing these explosives and their effects is given in Hoffman's online paper: from the pyrotechnics of the observed collapses of 9/11 to the breakthrough paper in 2009 by an international group of scientists led by Danish chemist Niels Harrit, which analyzed what apparently caused the buildings to fall.
In the classic paper Harrit et al in 2009, they concluded that the Towers & Building 7 all had clear evidence of unexploded nano-thermite. The production of this nano-thermite requires specialized processing and expertise, which the terrorists attacking the buildings by plane undoubtedly did not have. Papers from Lawrence Livermore Laboratories after 2000 were cited by Harritt et al on developing these processing capabilities for nano-thermite.
The terrorists that were blamed for hijacking the planes into the Towers were in fact not capable of this act involving specialized processing. Although they would may have been capable of hijacking the planes, the crashes and the fires they started could not have caused the buildings to completely collapse the way they did. The placing of the nano-thermite in the bringing of the buildings down apparently came from US sources. The building collapses were disguised to look like they came from the terrorists.
However, were the buildings brought down by just nanothermite? The answer is no. It was more involved than that.
As pointed out in Chapter 6 of National Swindle of the WTC, the high temperature melting of steel in the Tower explosions was accomplished by nano-thermite. As shown in Figure 1 from Steven Jones classic paper, melted steel was shown with a thermal spectrum on the South Tower just before its collapse. Only nano-thermite could produce that nearly 3,000º F needed to melt the steel. But nano-thermite was not the only thing used to collapse the buildings.
Figure 1. View of molten Fe (not Al) from steel pouring down that South Tower just at the initiation of collapse. This color spectrum indicates hot metal at 2800º F (from Jones)
Figure 2. Detailed view of a later collapse stage for the North Tower , which shows several pieces of wall from the Tower (ranging from a few hundred square feet up to a few thousand), and 100s of large pieces of the building everwhere, out to 300 feet or more away from the Tower. Substantial forces have broken up the building into a huge number of pieces and imparted considerable horizontal momentum to them. Clearly explosive forces are generating all of the momentum going sideways. Notice dust in the higher areas is apparently moving up, such as in the "ice-cream" feature.
Thus the facts show that 2 different explosive substances had to have been used: one producing the very high temperatures needed to melt the steel (as observed in Fig. 1) to start he rapid degradation of the structure, and one producing the very high velocities to take it apart by producing speeds that exceed the sound velociy of the medium, so there is no possibility of dispensing with any of the energy of the explosions by sound waves. The nanothermite explosion melting the metal intended to initiate the explosion, then more conventional explosives exploded on down the Tower to tear it apart. For example, in Figure 2 the large pieces of the North Tower shooting out 300 feet or more could have only been produced by that conventional material like TNT.
The fact that 2 explosives were used can be further shown by Figure 3, the panoramic view from the air of the North Tower exploding. From the view we clearly see 2 parts of the explosion -- one lower down with a thick dust of white material, and one higher up with a thick dust of darker material that is apparently moving up. The dual appearance is very explainable. The dust is the pulverized concrete of the building, and the darker material is so colored because it was from from the upper areas that were burning for about 1.5 hours before the explosions, and thus contains ashes. It is those areas where fires produced the onset temperature (observed in Harritt et al to be about 440º C, or just over 800º F) for the nano-thermite chemical reaction (2Al + Fe2O3 --> 2Fe + Al2O3) which is very exothermic and produces the nearly 3,000º F that melts steel. The very hot gray dust in that upper piece of the Tower are clearly moving up substantially -- all the way to just above the lefover smoke. However, the colder white dust of the lower bulk of the Tower is moving down. This lower portion is produced by a more conventional explosion, which is providing the large horizontal momentum.
Figure 3. Aerial view of the North Tower coming down, which shows white-colored material coming off in several directions from the lower bulk of the collapsing Tower, a color arising from all the concrete dust coming out as part of the material. Above that is a structure of grayer clouds formed from the high part of the building which had been on fire for 1 hour and 41 minutes. The hot rising gray cloud are produced by a nano-thermite explosion, whereas the colder white clouds come from a more conventional explosion.
In Figure 2, the "ice-cream cone" feature and other features that are rising are produced by nano-thermite. This is in the latter stage of the collapse and later convetional explosions mostly dominate. However, the "ice-cream cone" feature has been present for much of the collapse, and was formed by very hot dust rising, which finally plateued, forming the "ice-cream scoop" atop the cone.
The North Tower was actually taken down by using nanothermite on the upper floors and a conventional explosive below that. In the South Tower just before 10:00, less than an hour after the plane struck it lower down, they apparently had to set off the nano-thermite explosion early while the required threshold temperature for the chemical reaction was still available. A conventional explosion occurred 1st in the South Tower when the white dust squibs came out, and the nano-thermite explosion went off internally above that, forcing out the gray dust. That internal explosion then caused the top segment to come down. The North Tower remained hot enough to set off a nano-thermite reaction about 30 minutes later.
The title of Fetzer and Hightowers paper, "Is 9/11 Truth Based Upon a False Theory?" is misleading, because nano-thermite in the collapses is not a false theory. It was established in  and  that nano-thermite was involved in bringing the Towers down. While Fetzer and Hightower bring up a valid point that it is too slow to cause the widespread destruction that is observed, it simply provides a good argument that more was involved. Neils Harritt in general agrees with this, as he described how, with the use of nano-thermite in destruction, one has the option of putting in other explosives. The clear separation of the hot darker rising material and the white lower material shows that was in fact done.
It is worth noting that this flatly contradicts the theory that laser beams from space hit the Towers, which have been promulgated for over 5 years by Judy Woods and her followers despite repeated articles showing this could not be correct. Figure 3 is shown on the cover of her book, and they maintain that it purportedly shows the "dustifying" of the North Tower by a laser beam from space. Closer inspection as in Figure 2 shows nothing of the sort, but material of all different sizes going into a myriad of directions. Multiple explosions produced the observations shown.
[NOTES] Crockett Grabbe received his Ph.D. in Applied Physics from Caltech
in 1978, & was repeatedly listed in Who's Who in Science & Engineering
for over a decade. He was a research scientist in the Physics & Astronomy
Department at the Universiy of Iowa for 30 years, & now lives in Austin, TX.
 Crockett Grabbe, National Swindle of the WTC, online at http://www.amazon.com/dp/B00D5ZHWBW .
 Jim Hoffman, "Wake Up and Smell the Aluminothermic Nanocomposite Explosives", posted online at: http://911research.wtc7.net/essays/thermite/explosives_evidence_timeline.html
 "Neils H. Harritt et al "Active Thermitic Materials Discovered in Dust from the 9/11 World Trade Center Catastrophe," The Open Chemical Journal 2, 7-31 (2009), posted online at: http://www.benthamscience.com/open/tocpj/articles/V002/7TOCPJ.htm ?TOCPJ/2009/00000002/00000001/7TOCPJ.SGM
 "Nano-thermite" Wikipedia entry online at: http://en.wikipedia.org/wiki/Nano-thermite
 Steven E. Jones, "Why Indeed Did the WTC Buildings Completely Collapse," Journal of 911 Studies, 3, September (2006). Linked on the web out of http://www.Journalof911Studies.com . [Earlier version in Griffin & Scott (eds.), 9/11 and the American Empire: Intellectuals Speak Out (Interlink Publishing, Northhampton, MA, 2006].
 Jim Hoffman "Buidling a Better Mirage: NIST's 3-Year $20 million Coverup of the Crime of the Century," 9-11 Researh online at: http://911research.wtc7.net/essays/nist (This "nist" refers specifically to the NIST Committee appointed to investigate 9/11, not to the larger NIST body as a whole.)
 James Fetzer & Mark Hightower, "Is 9/11 Truth Based Upon a False Theory?" posted online at http://www.veteranstoday.com/2011/07/17/is-911-truth-based-upon-a-false-theory/
 "Aerial photos of the North Tower destruction" posted online by the 9-11 Research Project at: http://911research.wtc7.net/wtc/evidence/photos/collapses.html
 Neils H. Harritt in AE911Truth's interview on December 2, 2012 as part of the film they are preparing on "Experts Speak Out", posted at: http://www.youtube.com/watch?v=bksU6edN-EE
 Judy Wood, "Where Did the Towers Go?", online at: http://wheredidthetowersgo.com/