However, a less extreme view held by many 9/11 conspiracists is that the official version of events given by the US Government, about al-Qaeda being solely behind the devastating strikes on the Twin Towers and the Pentagon, are not a true account.
This conspiracy claims the attacks were directly funded by the Saudi Arabian government – now one of the US’s biggest allies in the Middle East.
The theory is bolstered by George W Bush’s controversial decision to black out 28 pages of a 2002 joint congressional intelligence inquiry into 9/11, redactions that have yet to be reversed.
While Democrat Hillary Clinton has been vying for votes from alien believers by promising to released top-secret fils on UFO visitations, if she makes the White House, Trump is appealing to so-called “911 truthers.”
Mr Trump appears to have aligned himself more with this theory judging by comments and attacks he has made on the former Bush administration.
During a campaign event in Bluffton, South Carolina, he said: “It wasn’t the Iraqis that knocked down the World Trade Center.
“We went after Iraq, we decimated the country, Iran’s taking over, but it wasn’t the Iraqis, you will find out who really knocked down the World Trade Center, because they have papers in there that are very secret, you may find it’s the Saudis, okay?
“But you will find out.”
This, and repeated statements Trump has made has been taken as an implied promise to declassify the blacked out pages of the report, which has led him to become an unlikely hero among some conspiracy quarters.
The Republican White House frontrunner has repeatedly referenced 9/11 during his campaign.
Fellow Republican candidate Jeb Bush pulled out of the race due to dwindling support just a week after a roasting from Mr Trump over his brother George “Dubya’s” war in Iraq and the reasons behind it.
Jeb had reportedly said he had never heard of the classified 28 pages and said when asked if he would like to see them before he stood down: “Yeah, I’d like to see ’em. You got ’em?”
Mr Trump, who outraged the world with his calls to ban Muslims in the US earlier this year, has even gained begrudging support from the far left anti-war group, Code Pink, due to his lambasting of the Bush administration.
The 28 pages were said to be withheld on National Security grounds, but Trump is not the first politician to try to get them out.
Republican candidate Rand Paul, introduced Senate Bill 1471, which attempted to direct President Obama to release them, and also vowed pledged to release them himself if elected. Green Party candidate Jill Stein has called for the release.
In 2003 Hillary Clinton signed a letter to President Bush demanding the release of the 28 pages from the 9/11 inquiry but has reportedly remained silent on the subject.