A memorial ceremony is under way at the site of New York's World Trade Center as the US marks the 25th anniversary of the 9/11 attacks
Relatives of the victims are reading out the names of those killed as seven moments of silence - six marking the times the planes crashed and buildings fell, and one to honour those who have since died from 9/11-related illnesses - are observed
Vice-President JD Vance and all living former US presidents are at the ceremony - here's a look at how the attacks are being remembered throughout the day
On 11 September 2001, a total of 2,977 people were killed - about 2,700 died after hijackers crashed two planes into the Twin Towers of the World Trade Center
President Donald Trump is at a separate remembrance ceremony in honour of the 184 people killed at the Pentagon when American Airlines Flight 77 crashed into the building
Another plane crashed in a field in Pennsylvania after passengers fought back against the hijackers
"Everybody helped everybody," a New Yorker tells the BBC as he says the togetherness that emerged from the attacks was the "best part that came out of that terrible day"
Image source, ReutersPresident Donald Trump is now speaking at the Pentagon 9/11 ceremony.
"In 25 years, a generation has passed since the terror attacks," he says. "Yet time has not dimmed the honour of that day our country came face-to-face with true evil."
You can follow his remarks live by pressing watch live above.
Bernd Debusmann Jr
White House reporter
Next up at the Pentagon 9/11 ceremony is Defence Secretary Pete Hegseth, who was a member of the Reserved Officers Training Corps at Princeton when 9/11 took place.
Hegseth has focused his speech heavily on the military response to 9/11, including the massive recruitment numbers that the military saw immediately after the attacks and those who served overseas.
"We fought foreign wars, a generation of sacrifice, of valor, selfless and steadfast," he said. "Even if imperfect, those conflicts were our retribution."
Hegseth has also repeatedly mentioned what he termed the "Islamist threat" to the US - a fight he says continues today.
"There are still enemies who hate us. Every day, enemies plot to curb our power and kill our citizens, including from Islamic terrorists abroad and at home. But we are ever vigilant, especially this place," he said.
The defence secretary has explicitly linked the fight against terrorism to the current campaign in Iran.
"Over the past six months, we have laid waste to the world's most prolific state sponsor of terrorism. Our warriors have fought an Islamic theocracy that has wished us death for nearly half a century," Hegseth said.
Grace Eliza Goodwin
Reporting from the 9/11 memorial in New York
Gunter Engels
Back at the 9/11 Memorial in New York, I caught up with Gunter Engels, a 55-year-old from Belgium, who says everyone in his generation remembers exactly where they were on that day - even in Europe.
He recalls every channel on TV showing the news of the attacks in place of regular programming.
“The first thought in mind for me was ‘this is the end of the world,” he says.
“They're attacking America, and when things like that happen, I think they affect the whole world,” he adds. “The world has never been the same after 9/11.”
His own life changed that day too - his former brother-in-law was working in the Twin Towers when the planes hit.
He never came down that day, Engels says.
“We had a very good bond even after we were not family anymore,” Engels says. He says he tried contacting the family that day to check in, but it was “not easy, all the lines were too busy”.
“We tried a few weeks later, and then the family confirmed that he was missing,” Engels says.
“He's never been found.”
The crowd at the National Memorial in New York is taking another moment of silence after a fifth bell rang out at 10:03 EDT.
This commemorates the exact minute Flight 93 crashed in an empty field near Shanksville, Pennsylvania, after passengers attempted to take control of the plane back from hijackers.
Image source, Getty ImagesVisitors explore the Flight 93 National Memorial in Somerset County, Pennsylvania
Approximately 140 miles away from the Pentagon's memorial to the 11 September attacks, on Somerset County, Pennsylvania, in the borough of Shanksville, is the site where United Airlines Flight 93 crashed that day after passengers attempted to regain control of the aircraft from the hijackers.
It’s intended target was believed to be either the US Capitol Building or the White House in Washington DC.
At the centre of the memorial on a hill overlooking the crash site is a white marble wall of names which, along with an observation platform, is aligned with the path of the flight.
Bernd Debusmann Jr
White House reporter
Image source, Getty ImagesBack at the Pentagon 9/11 ceremony, we've just heard from former National Security Adviser and Secretary of State Condoleezza Rice, who spoke of the significance of the "out of the blue" assault on the United States.
"I was at my desk at the White House that day when my executive assistant, a young army officer, told me that a plane had hit the World Trade Center. What a strange accident, I thought," she recalled.
She was then moved to a bunker here at the White House once it became clear an attack was under way when the second aircraft struck in New York.
Rice paints a picture of chaos as the attacks unfolded, unable to get in touch with then Defence Secretary Donald Rumsfeld in the wake of the attack on the Pentagon.
"Behind every name that we recite, there is a story, a life that mattered, a future unfulfilled, a void, a vast empty space in the heart of a husband, a wife, a son, a daughter, a sibling, a colleague, or a friend," she said.
"We come together today to say that they will never be forgotten. forgotten, and to honour their memory."
Now, a fourth bell and fourth moment of silence at New York City's memorial to those who perished 25 years ago.
Beginning at 09:59 EDT, they mark the exact moment the South Tower of the World Trade Center collapsed.
You can follow along by pressing watch live above, where we'll also be carrying President Trump's remarks at the Pentagon 9/11 ceremony, beginning shortly.
Grace Eliza Goodwin
Reporting from the 9/11 Memorial in New York
Rich Baktis
Here in New York, Rich Baktis tells me how he was in high school on Long Island when the 9/11 attacks happened.
“It was chaos," the 41-year-old recalls. "Just everybody trying to find people."
He didn’t know anyone at the time who worked in the Twin Towers, but had family members who were in the area.
He says he wants younger generations to understand the magnitude of unity, patriotism, and bravery that filled the city in the aftermath.
“Everybody came together, and everybody helped everybody, and working down on the pile, even outside communities,” he says.
“Everybody lost people,” he says. But the togetherness and care that he felt in the aftermath was the “best part that came out of that terrible day”.
Events commemorating those who died in the 9/11 attacks 25 years ago have now been taking place across the US for a few hours now.
We're currently following the New York and Pentagon ceremonies in the stream at the top of the page, which began a short while ago.
Here's a reminder of what else has been happening - and timings for the rest of the day:
In New York
In Pennsylvania
In Virginia
Image source, Getty ImagesDefence Secretary Pete Hegseth and former Secretary of State Condoleezza Rice
We can now bring you more pictures of US officials attending the memorial ceremony at the Pentagon, including Defence Secretary Pete Hegseth, Secretary of State Marco Rubio and others.
As a reminder, ceremonies are currently under way at both the Pentagon in Virginia and the World Trade Center in Manhattan.
President Trump and his wife, Melania, were pictured earlier attending the Pentagon ceremony.
Image source, Getty ImagesFBI Director Kash Patel
Image source, Getty ImagesSecretary of State Marco Rubio and Secretary of Treasury Scott Bessent
Image source, Getty ImagesDonald Trump Jr and Jennifer Hegseth, wife of Defence Secretary Pete Hegseth
Gary O'Donoghue
Chief North America correspondent, in Washington DC
Image source, Getty ImagesShortly after dawn, as has become the ritual, the attack on the Pentagon was marked by the unfurling of the Stars and Stripes on the side of the building where Flight 77 struck at 09:37 EDT in the morning 25 years ago.
One hundred and twenty five people inside were killed, along with all 59 crew and passengers on American Airlines Flight 77.
The facade of this symbol of American power was rebuilt within a year of America's worst-ever terrorist attack. A chapel of remembrance now marks the spot where the hijackers aimed the plane. A further memorial is being constructed which will open later this decade.
Despite the attack that day, the building never stopped functioning; the US was under attack, and the men and women of the world's most powerful military immediately set about planning the country's response.
Twenty five years on, few would have imagined that American soldiers would spend two decades in Afghanistan, and even fewer would have imagined they would end up leaving in an ignominious and chaotic fashion – with the return of the Taliban who had been al-Qaeda's protectors in the first place.
Donald Trump’s decision to mark this day at the Pentagon instead of Ground Zero in New York has been somewhat controversial.
His words will be scrutinised around the world.
Former Presidents Bill Clinton, George W Bush, Barack Obama and Joe Biden are all in attendance at the 9/11 ceremony in New York today.
Current President Donald Trump is not in New York, but is instead attending a 9/11 ceremony at the Pentagon, which was attacked by a third hijacked plane on 11 September 2001.
Vice-President JD Vance is attending today's ceremony in Manhattan.
A third bell has just rung out at the National 9/11 Memorial in Manhattan, followed by another moment of silence.
It marks the exact minute Flight 77 struck the Pentagon in Virginia at 09:37 EDT on 11 September 2001.
As a reminder, a separate ceremony is being held at the Pentagon, which is being attended by President Donald Trump.
Terry Strada
A short while ago at the New York 9/11 ceremony, Terry Strada, the wife of a victim of the attacks, took a moment after reading her husband's name to call out Saudi Arabia's alleged role in the crimes.
"How can it be 25 years and still, we have no justice for the role that Saudi Arabia played in your murder?" she said at the podium, to loud applause from the audience.
The country "fomented a rancid culture of anti-American terrorism around the globe", she added.
Image source, Getty ImagesThe National 9/11 Pentagon Memorial is located just southwest of the Pentagon in Arlington County, Virginia, across the Potomac River from Washington, DC and commemorates the 184 people who died in the building and on American Airlines Flight 77 during the 11 September 2001 attack.
The permanent outdoor memorial opened on 11 September 2008, seven years after the attack, replacing earlier temporary memorials. In the aftermath of 9/11, a huge US flag was draped across the damaged side of the building.
The design includes illuminated benches for each victim, arranged according to their ages, from Dana Falkenberg, who was 3, to John Yamnicky Sr, who was 71, and engraved with their names.
Bernd Debusmann Jr
White House reporter
At the 9/11 ceremony at the Pentagon, Trump is sitting beside Melania, near a uniformed member of the US Army reading the names of the fallen as a bell tolls.
To Melania's left, on the opposite edge of the stage, is Pete Hegseth and Condoleezza Rice, who was serving as National Security Adviser in the Bush administration when the attacks took place.
Others in attendance include Attorney General Todd Blanche, Education Secretary Linda McMahon, Energy Secretary Chris Wright and Dan Caine, the chairman of the Joint Chiefs of Staff.
As a young Air Force officer, General Caine was among the pilots who patrolled Washington's airspace in the wake of the attacks.
Image source, Getty ImagesWe can now bring you another picture of US President Donald Trump at the Pentagon 9/11 memorial, alongside the First Lady Melania Trump.
Attendees could also be seen sitting outside on the cloudy day in Virginia.
As a reminder, the service was due to begin at 09:00 EDT (13:00 GMT, 14:00 BST).
Other events in Virginia included a community remembrance ceremony in Manassas Park earlier.
Image source, Getty Images
As names continue to be read out, iconic cellist Yo-Yo Ma is performing a piece on the cello.
Kayla Epstein
Reporting from NewYork
An FDNY fireboat sprays water and as a fleet of vessels blow their horns on the Hudson River.
A parade of fireboats is now making its way up the Hudson River.
Several of the boats are performing a water salute, spraying red, white and blue water.
Their horns echo across the waterfront as just a short walk away, family members read the names of the thousands of people who died on 11 September.
Back at the 9/11 ceremony in New York, several former US presidents are listening to names being read out, including Barack Obama, Joe Biden, Bill Clinton and George W Bush.
Image source, Getty ImagesJoe Biden and Jill Biden share an embrace at the 9/11 ceremony, standing next to George W Bush
Image source, Getty ImagesFormer President Bill Clinton and former Secretary of State Hillary Clinton stand next to former President Barack Obama and Michelle Obama
