ARLINGTON, VIRGINIA - SEPTEMBER 11: U.S. President Joe Biden participates in a wreath-laying ceremony commemorating the 21st anniversary of the crash of American Airlines Flight 77 into the Pentagon during the September 11th terrorist attacks at the 9/11 Pentagon Memorial on 11 September, 2022 in Arlington, Virginia. The nation is marking the twenty-first anniversary of the terror attacks of 11 September, 2001, when the terrorist group al-Qaeda flew hijacked airplanes into the World Trade Center, Shanksville, PA and the Pentagon, killing nearly 3,000 people.
ARLINGTON, VIRGINIA - SEPTEMBER 11: U.S. President Joe Biden participates in a wreath-laying ceremony commemorating the 21st anniversary of the crash of American Airlines Flight 77 into the Pentagon during the September 11th terrorist attacks at the 9/11 Pentagon Memorial on 11 September, 2022 in Arlington, Virginia. The nation is marking the twenty-first anniversary of the terror attacks of 11 September, 2001, when the terrorist group al-Qaeda flew hijacked airplanes into the World Trade Center, Shanksville, PA and the Pentagon, killing nearly 3,000 people.

Sympathy, solidarity as US marks 21st anniversary of 9/11

Americans on Sunday marked the 21st anniversary of the 9/11 attacks, with president Joe Biden visiting the Pentagon and New Yorkers honoring the nearly 3,000 people killed when hijacked planes destroyed the Twin Towers.

Relatives of victims, police officers, firefighters and city leaders gathered at the National 11 September Memorial in Lower Manhattan, where the names of those who died were read aloud, as they have been every year since the deadliest single attack on US soil.

They rang bells and held moments of silence at 8:46am and 9:03am (1246 and 1303 GMT), the precise times the passenger jets struck the World Trade Center's North and South Towers.

HOUSTON, TEXAS - 10 SEPTEMBER: Elena Ramos pays her respects to her brother, Senior airman Elijah Reyes Posana, at the Houston National Cemetery on 10 September, 2022 in Houston, Texas. People around Houston have begun visiting and preparing ahead of the 21st anniversary of the 9/11 terrorist attacks in New York City. Nearly 3,000 people were killed when terrorists hijacked four passenger planes and crashed them into the twin towers at the World Trade Center on 11 September, 2001.

Biden commemorated the anniversary at the Pentagon, where Al-Qaeda hijackers crashed a plane into the massive building that serves as Defense Department headquarters.

In a steady rain, the president approached a wreath of flowers outside the building and placed his hand over his heart.

"Twenty-one years later, we keep alive the memory of all the precious lives stolen from us at Ground Zero, in Shanksville, Pennsylvania, and at the Pentagon," Biden said on Twitter ahead of delivering remarks.

"To the families and loved ones who still feel the ache, Jill and I hold you close in our hearts."

NEW YORK, NEW YORK - 11 SEPTEMBER: Families of the victims of the 9/11 terror attack attend the annual 9/11 Commemoration Ceremony at the National 9/11 Memorial and Museum on 11 September, 2022 in New York City. This year marks the 21st anniversary of the terror attacks of 11 September, 2001, when the terrorist group al-Qaeda flew hijacked airplanes into the World Trade Center, Shanksville, PA and the Pentagon, killing nearly 3,000 people. Vice President Kamala Harris and Secretary of Homeland Security Alejandro N. Mayorkas were in attendance for this years ceremony.

Al-Qaeda hijacked a total of four planes. The third hit the Pentagon and the fourth, Flight 93, crashed in a field in Pennsylvania after passengers launched a revolt onboard.

Vice President Kamala Harris, Homeland Security Secretary Alejandro Mayorkas and Mayor Eric Adams were among the dignitaries attending the New York ceremony, where relatives hugged one another, placed flowers at the memorial and held placards or wore shirts with images of their lost loved ones.

"While the grief recedes a bit with time, the permanent absence of my father is just as palpable as it ever was," the son of Jon Leslie Albert said after reading several victims' names, including his father's.

Flowers and US flags are seen on the 9/11 Memorial in New York, on 10 September, 2022, one day before the 21st anniversary of the attacks on the World Trade Center, Pentagon, and Shanksville, Pennsylvania.

Messages of sympathy and support came from outside the country, including from NATO Secretary General Jens Stoltenberg and Ukrainian President Volodymyr Zelensky, who called September 11 "one of the most tragic days" for the US and the world.

"Facing missile attacks daily, Ukraine knows well what terrorism is and sincerely sympathizes with the American people," Zelensky tweeted, referring to the Russian invasion of his country that has left thousands dead.

New York was illuminated late Saturday by a "Tribute in Light" that showed two blue beams projecting into the night sky symbolizing the Twin Towers.