The underlying issue stems from the official NIST Report (NIST NCSTAR 1-9- Nov. 2008) which basically contends that for the first time in history, the symmetrical, complete collapse of a large, fire protected, 47 story steel framed building was said to be fire induced.
Since the issuance of this NIST Report, members of Architects and Engineers for 9/11 Truth, as well as other independent researchers have vigorously disputed the conclusions of the NIST and its Report.