Starting with a parade staged by emergency services personnel, the ceremony took place in the area where the Twin Towers once stood. Former Presidents Barack Obama and Bill Clinton, and relatives of the nearly 3,000 victims, took part in the official act.
World leaders sent words of remembrance and consolation to the victims, including European Commission President Ursula von der Leyen, Germany's Chancellor Angela Merkel, and France's President Emmanuel Macron.
The Russian ambassador to the U.S., Anatoly Antonov, also referred to the attacks, noting his country's desire to put aside differences and cooperate for the benefit of security.
Tomorrow, we will commemorate the 20th anniversary of the 9/11 attacks.
20 years after the day that changed our world forever, family members of 9/11 victims will come together to read aloud the names of all those killed.
Likewise, Cuba's President Miguel Diaz-Canel and Venezuela's President Nicolas Maduro condemned the 9/11 attacks while rejecting all forms of aggression and violence affecting the life and peace of people.
The act of remembrance comes amid the debate generated by the hasty withdrawal of U.S. troops from Afghanistan after 20 years of war and amid the advance of Taliban militias in the Central Asia nation last month.
On Sept. 11, 2001, Nineteen men from the Al Qaeda terrorist group hijacked four commercial airliners and targeted major U.S. landmarks such as the World Trade Center, the Pentagon, and the White House.
A total of 2,977 lives were lost in the attacks on the Twin Towers in New York. Among these victims were 343 firefighters, 23 police officers, and 37 port authority officers. The rest of the victims were civilians.