Almost 3,000 people died when a quartet of hijacked planes crashed into the World Trade Center skyscrapers, the Pentagon, and a field near Shanksville, Pennsylvania on September 11, 2001.
Perhaps predictably, social media was also awash with emotion, with the hashtag #NeverForget trending from the turn of midnight onward.
#NeverForget— WhoKilledKevinCrehan (@SydneyAtheist) September 11, 2017
The ideology that killed almost 3,000 Americans sixteen years ago is still around and being excused by cowardly politicians.
Sometimes I wish that time had just stuck at Sept 10, 2001. #9/11 #NeverForget— Ian Williams (@Scscottish) September 11, 2017
President Donald Trump, a native New Yorker, is marking the anniversary for the first time as the country's leader today.
He will observe a moment of silence at the time the first airliner hit the towers. Subsequently, he will take part in a 9/11 observance at the Pentagon.
Sixteen years after the World Trade Center was reduced to a sprawling mound of rubble, the case against the plot's alleged mastermind and his confederates looks set to drag on for a great deal longer yet.
Khalid Sheikh Mohammed has been accused of being 9/11's "architect" — and he and his four alleged co-conspirators all face the death penalty if and when convicted. However, as of September 2017, the case remains at the pre-trial stages — and the accused remain in solitary detention in Guantanamo Bay, where they have languished for 14 years.
A full-fledged trial is years away, if it takes place at all — at a hearing in August, prosecutors suggested an early 2019 trial start date. They would be tried at the military detention center, on charges of terrorism and over 3,000 counts of murder, facing a jury comprised of military officers. Such is the sluggish pace of prosecution, some of the 9/11 victims' families have gone as far as to call for securing non-fatal plea deals with the accused.
Mohammed allegedly mapped out the 9/11 plot, secured Osama bin Laden's support, trained hijackers in Afghanistan and Pakistan and oversaw operations — his co-conspirators (Walid Bin Attash, Ramzi bin al-Shibh, Ammar al-Baluchi and Mustafa al-Hawsawi) purportedly trained the 19 hijackers, arranged travel and flight school courses, and provided funds for the operation.
While the case against Mohammed is said to be strong, as part of the CIA's torture program, he was waterboarded 183 times in a single month, subject to sleep deprivation and even endured "rectal hydration" — a grueling ordeal that gives the accused's defense team immense ammunition.
Originally opened in 2002 as a temporary camp to hold individuals captured in Afghanistan and believed to be connected to al-Qaeda, Guantanamo Bay quickly became a symbol of the US' heavy-handed response to 9/11. At its peak in July 2003, it held around 680 prisoners, although this had fallen to nearly 240 when Barack Obama assumed office in 2009.
Obama had run on an explicit platform of closing "Gitmo" — although in the event, the President opted for a number of prisoner transfer deals with Saudi Arabia, Oman, and other countries in the Middle East and North Africa. By the time Donald Trump assumed office — a man who pledged to "load it up" with more "bad dudes" — its detainee population had fallen to 41, of which 26 are "forever prisoners" who will be held indefinitely without charge.
Critics say Guantanamo Bay violates human rights by holding individuals indefinitely without charge, feeds anti-American feeling abroad, and is needlessly expensive — however, polls suggest 56 percent of Americans want Guantanamo kept open. Moreover, Secretary of State Rex Tillerson intends to sack the envoy responsible for its closure, and Attorney General Jeff Sessions has called it a "very fine place" to interrogate and prosecute terrorism suspects.