The co-ordinated outrages of that day left almost 3,000 US citizens dead and made explicit the reality that America – and other Western nations – were seen as legitimate targets by radical Islamists.
The then US president, George W Bush, wished to hit back hard against any individuals or groups that might be planning similar atrocities. The use of Guantanamo to detain and interrogate those suspected of planning further attacks was, at first, understandable.
But it did not take long for the uncomfortable truth about what was happening at Guantanamo Bay to become public. The facility was being used for the torture of suspects, many of whom faced no charges and against whom evidence was slender or nonexistent.
The reputation of America as the “land of the free” is deeply damaged by the continued existence of Guantanamo Bay as a detention centre. What has been done there in the name of justice is disgraceful.
Departing US President Barack Obama spoke of his desire to close the facility but, as he prepares to leave office, it remains.
Remarks made by president-elect Donald Trump suggest that the detention centre will remain operational indefinitely.
To Trump supporters, whipped up by his anti-Muslim comments and his simplistic promises to shut down terrorist cells, Guantanamo represents a noble fightback against extremists.
Fifteen years after it began taking in prisoners, Guantanamo Bay should be a source of shame to America but, under Trump’s presidency, we fear it will become a symbol of the sort of “great” nation he and his supporters wish to create.
President Obama should have closed the facility before it fell into Trump’s hands.