Video above: Ceremony being held in New York to honor 9/11 victimsAmericans are remembering 9/11 with moments of silence, readings of victims' names, volunteer work and other tributes 21 years after the deadliest terror attack on U.S. soil.A tolling bell and a moment of silence began the commemoration at ground zero in New York, where the World Trade Center's twin towers were destroyed by the hijacked-plane attacks of Sept. 11, 2001. Victims’ relatives and dignitaries also convened at the two other attack sites, the Pentagon and a field in Pennsylvania.Other communities around the country are marking the day with candlelight vigils, interfaith services and other commemorations. Some Americans are joining in volunteer projects on a day that is federally recognized as both Patriot Day and a National Day of Service and Remembrance.The observances follow a fraught milestone anniversary last year. It came weeks after the chaotic and humbling end of the Afghanistan war that the U.S. launched in response to the attacks.But if this Sept. 11 may be less of an inflection point, it remains a point for reflection on the attack that killed nearly 3,000 people, spurred a U.S. “war on terror” worldwide and reconfigured national security policy.It also stirred — for a time — a sense of national pride and unity for many, while subjecting Muslim Americans to years of suspicion and bigotry and engendering debate over the balance between safety and civil liberties. In ways both subtle and plain, the aftermath of 9/11 ripples through American politics and public life to this day.Live video: Ceremony held at the Pentagon to honor lives lost on 9/11 And the attacks have cast a long shadow into the personal lives of thousands of people who survived, responded or lost loved ones, friends and colleagues.More than 70 of Sekou Siby's co-workers perished at Windows on the World, the restaurant atop the trade center's north tower. Siby had been scheduled to work that morning until another cook asked him to switch shifts.Siby never took a restaurant job again; it would have brought back too many memories. The Ivorian immigrant wrestled with how to comprehend such horror in a country where he'd come looking for a better life.He found it difficult to form the type of close, family-like friendships he and his Windows on the World co-workers had shared. It was too painful, he had learned, to become attached to people when “you have no control over what’s going to happen to them next.”“Every 9/11 is a reminder of what I lost that I can never recover,” says Siby, who is now president and CEO of ROC United. The restaurant workers' advocacy group evolved from a relief center for Windows on the World workers who lost their jobs when the twin towers fell.On Sunday, President Joe Biden plans to speak and lay a wreath at the Pentagon, while First Lady Jill Biden is scheduled to speak in Shanksville, Pennsylvania, where one of the hijacked planes went down after passengers and crew members tried to storm the cockpit as the hijackers headed for Washington. Al-Qaida conspirators had seized control of the jets to use them as passenger-filled missiles.Vice President Kamala Harris and husband Doug Emhoff joined the observance at the National Sept. 11 Memorial in New York, but by tradition, no political figures speak at the ground zero ceremony. It centers instead on victims' relatives reading aloud the names of the dead.Readers often add personal remarks that form an alloy of American sentiments about Sept. 11 — grief, anger, toughness, appreciation for first responders and the military, appeals to patriotism, hopes for peace, occasional political barbs, and a poignant accounting of the graduations, weddings, births and daily lives that victims have missed.Some relatives also lament that a nation which came together — to some extent — after the attacks has since splintered apart. So much so that federal law enforcement and intelligence agencies, which were reshaped to focus on international terrorism after 9/11, now see the threat of domestic violent extremism as equally urgent.

President Joe Biden will visit all three 9/11 memorial sites to commemorate the 20th anniversary of the Sept. 11 attacks and pay his respects to the nearly 3,000 people killed that day. Biden will visit ground zero in New York City, the Pentagon and the memorial outside Shanksville, Pennsylvania, where United Flight 93 was forced down, the White House said Saturday.Vice President Kamala Harris will travel to Shanksville, Pennsylvania, for a separate event before joining the president at the Pentagon, the White House said.Biden's itinerary is similar to the one President Barack Obama followed in 2011 on the 10th anniversary of the attacks. Obama's visit to New York City coincided with the opening of memorial at the site where the iconic World Trade Center towers once stood.Next Saturday's anniversary falls less than two weeks after the end of the nearly two-decade-long U.S. war in Afghanistan. The war was launched weeks after the 9/11 attacks to retaliate against the al-Qaida plotters and the Taliban, who provided them safe haven. Biden has found support from the public for ending the conflict but has faced sharp criticism, even from allies, for the chaotic evacuation of U.S. troops and allied Afghans during the final two weeks of August.Biden on Friday directed the declassification of certain documents related to the Sept. 11 attacks in a gesture toward victims' families who have long sought the records in hopes of implicating the Saudi government. The conflict between the government and the families over what classified information could be made public came into the open last month after many relatives, survivors and first responders said they would object to Biden's participation in 9/11 memorial events if the documents remained classified.___Superville reported from Wilmington, Delaware.