Subscribe to receive The 45th newsletter in your inbox.

Americans looked back on the September 11 attacks Tuesday with solemn ceremonies, volunteer service and a presidential tribute to "the moment when America fought back". Thousands of 9/11 victims' relatives, survivors and rescuers gathered at the memorial plaza where the World Trade Center's twin towers once stood, commemorating the deadliest terror attack on US soil.

US President Donald Trump and First Lady Melania Trump visited a memorial honouring the passengers who brought down United Airlines Flight 93 into an unpopulated field in Pennsylvania. 

"America's future is not written by our enemies. America's future is written by our heroes," Trump said. "As long as this monument stands, as long as this memorial endures, brave patriots will rise up in America's hours of need and they, too, will fight back."