Another plane, United Airlines Flight 93, crashed in a field in Shanksville, Pennsylvania.
It is believed hijackers were planning to aim that aircraft at the Congress or White House in Washington DC before it went down, killing all 40 people aboard.
Cockpit voice recordings of the hijackers and mobile phone calls from those aboard to loved ones indicate passengers tried to fight their way into the cockpit to regain control before the plotters nosedived the plane.
President Trump praised the passengers’ “incredible valor” and said their revolt was “the moment America fought back”.
He said: “A band of brave patriots turned the tide on our nation’s enemies and joined the immortal rank of American heroes.”
Donald Trump is the third sitting president to attend the crash site, 70 miles south-east of Pittsburgh.
Senator John Cornyn, a Texas Republican, was among those who noted this is the first year that Americans born after the attacks will be old enough to enlist in the US military.
During remarks at the Pentagon, VP Mike Pence told audience members they “must learn the lessons of 9/11 and remain ever vigilant”.
The ceremony in New York was attended by New York Governor Andrew Cuomo, US ambassador to the United Nations Nikki Haley and Mayor Bill de Blasio, as well as former mayors Michael Bloomberg and Rudy Giuliani.
Relatives of victims read out the names of the dead, and moments of silence were observed at 08:46 and 09:03 to mark the times when passenger jets struck the two skyscrapers.
In the years since the attacks, cancer cases in lower Manhattan – especially among first responders who dug through the toxic rubble – have increased.
The 9/11 Victims’ Compensation Fund has paid out $4 billion to fund medical expenses for survivors of the terror attacks.
According to the World Trade Center Health Program, nearly 10,000 of them have had some form of cancer.
Tens of thousands of people inhaled fumes in the days after the attack, and the number of patients coming forward with tumors has increased in recent years, according to the fund.
The names of 648 co-workers who died in the 9/11 attacks were arranged on the Cantor Fitzgerald section at the Ground Zero memorial according to who knew whom best, it was revealed.
For the last 12 years, passersby may have assumed that the names on the Cantor Fitzgerald section of the bronze panels that wrap halfway around the north pool of the 9/11 Memorial were sorted randomly, rather than by age or initial.
But it has now been revealed that they were in fact arranged based on “meaningful adjacencies”, allowing the names of best friends and co-working relatives to sit side by side.
“They weren’t people who just worked together and went home. They made up the fabric of their lives,” Danielle Gardner – whose brother Douglas did not survive the attacks – told the New York Post.
Investment bank Cantor Fitzgerald lost almost three quarters of its workforce when American Airlines Flight 11 slammed into the north tower a few stories below is offices on floors 101 and 105.
More than any other financial firm, the bank was seen as a family-run operation that fostered close friendships and saw brothers, aunts, uncles and even parents working shoulder to shoulder.
The change was made after a campaign by survivors and relatives that fought for “meaningful adjacencies” rather than those organized according to age or initial.
Each name was inputted into a specifically-designed computer programme that grouped colleagues together according to who knew who best.
Co-workers, close relatives, best friends and even a beloved baby sitter are clustered on the memorial, according to the New York Post.
Danielle Gardner has also completed Out of the Clear Blue Sky, a documentary about the unprecedented losses suffered by the company.
The names of 648 co-workers who died in the 9/11 attacks were arranged on the Cantor Fitzgerald section at the Ground Zero memorial according to who knew whom best
Douglas Gardner, 39, worked on the firm for several years with childhood friend Douglas Gurian. An executive director by the time he left, Douglas Gardner and Douglas Gurian, 38, had known each other since before the first grade. They spent summers together on Fire Island, married about the same time – Gurian proposed at Gardner’s summer home – and even had children at about the same time, said the Post.
Tragically, Douglas Gardner was attending a meeting at Windows on the World, a restaurant on the top floor of the North Tower, when the building was struck. He and Douglas Gurian, a broker, did not make it out alive. Their names are close, with only trader Calvin Gooding between them, according to the Post.
Calvin Gooding, 38, met Douglas Gardner in college. The night before all three men met their tragic fate, Danielle Gardner called Calvin Gooding to ask if he would sing and speak at her brother’s 40th birthday party, set to happen on October 5, 2001, she told the Post.
“I’ll definitely want to perform and give a speech,” she said.
Mark Colaio, 34, and a senior managing director, talked bond broker brother Stephen, 32, into joining the tightly-knit firm. The elder brother often had a group of 25 employees over for parties at his Manhattan apartment and out to his Montauk beach house, his sister Jean told the Post.
“They spent a lot of time outside work and shared a lot of special times,” said Jean Colaio, adding that “they really looked out for each other – while working, as friends, and, I’m sure, on that day”.
Joining the Colaio brothers nearby is Thomas Pedicini, 30. As Mark Colaio’s brother-in-law, he was recruited into the firm’s equity department, the Post noted.
Stephen Hoffman, 36, and Robert Jordan, 34, went to college together and ended up at the firm as bond traders, Hoffman’s brother Greg told the Post.
They surfed and played golf together – they both even married school teachers, Greg Hoffman noted. With so much in common, the two families were very close, even joining Stephen Hoffman’s family for trips to the Jersey Shore.
“That’s the way those guys lived,” Greg Hoffman said, adding that “in the end, that’s the way they died, together”.
Daniel Shea, 37, and his brother Joseph Shea, 47, were both managing directors by the time they found themselves with a familiar intern – former babysitter Amy O’Doherty. Having known her since she was 13, it was only natural to offer her a tryout after watching how easily she multi-tasked juggling the kids and all their various activities.
“She handled it so effortlessly, and the kids were crazy about her,” Nancy Shea, Joseph’s widow, told the Post.
“She was indispensable to our family.”
Hired shortly after graduation in 2000, Amy O’Doherty was with the firm just over a year when the terror attacks occurred, Nancy Shea noted.
Rosanne Lang, 50, and an equities trader with the firm, was searched for by nephew Brendan Lang, 30, after the first plane hit, according to a relative who spoke to the Post.
Brendan Lang called his parents telling them he was going to find his aunt, he had a plan he said. He was a project manager working in the South Tower – across from his aunt’s North Tower office. Neither made it out alive, but Cantor placed their names next to each other despite Brendan Lang having never worked for the firm.
Bill “Scoop” Esposito, 52, and a partner at the firm, had survived the first World Trade Center bombing in 1993. He and bond broker Peter Milano, 43, led a pregnant women to safety during that attack, a relative told the Post.
It took them more than two hours to make it to the ground floor via the stairwell, but they did it, and Bill Esposito once again came to the rescue.
“When they got to the bottom floor, glass was falling. He pushed Peter out of the way and saved his life,” Bill Esposito’s daughter Susan told the Post.
Bill Esposito also bought senior vice president Thomas Strada’s wife a baby gift the day before the attacks, she had given birth only days earlier, she noted.
“Everybody knew everybody, there were friends of friends of friends,” she told the Post.
The sudden closure of many American diplomatic missions in North Africa and Middle East were prompted after the US intercepted conversations between two senior al-Qaeda leaders.
The chatter, involving top leader Ayman al-Zawahiri, represented one of the most serious plots since the 9/11 attacks, the New York Times wrote.
The US earlier said the closures in North Africa and the Middle East were “out of an abundance of caution”.
Some 20 US embassies and consulates were shut on Sunday.
A state department global travel alert, issued last week, is also in force until the end of August.
US diplomatic posts in Abu Dhabi, Amman, Cairo, Riyadh, Dhahran, Jeddah, Doha, Dubai, Kuwait, Manama, Muscat, Sanaa and Tripoli will remain closed until Saturday.
Several European countries have also temporarily shut missions in Yemen and the UK Foreign Office is advising against all travel to the country.
Both the White House and the US state department said the threat came from al-Qaeda in the Arabian Peninsula (AQAP), but refused to divulge further details.
Some 20 US embassies and consulates in North Africa and Middle East were shut
But according to the New York Times, the US intercepted communications between Ayman al-Zawahiri and the group’s head in Yemen, Nasser al-Wuhayshi.
The paper said that no targets had been singled out in the discussions, but that a possible attack appeared to be imminent.
A US official told the Associated Press news agency that Ayman al-Zawahiri’s message had been picked up several weeks ago and appeared initially targeted at Yemen.
US lawmakers have said it was a huge plot in the final stages, but have offered no specifics.
On Monday, a top member of the House intelligence committee Dutch Ruppersberger told CNN the warnings were not designed to frighten Americans, though he said a planned attack could be “anywhere”.
“Americans should live their lives… we just want them to be aware,” Representative Dutch Ruppersberger said.
White House spokesman Jay Carney said he could not be “specific” about the threats.
He said: “Our current information suggests that al-Qaeda and affiliated organizations continue to plan terrorist attacks both in the region and beyond. And our information suggests that they may focus efforts to conduct attacks in the period between now and the end of August.”
Meanwhile, officials in Yemen have released the names of 25 al-Qaeda suspects, saying they had been planning attacks targeting “foreign offices and organizations and Yemeni installations” in the capital of Sanaa and other cities across the country.
There was also increased security at government buildings and checkpoints in Yemen on Monday.
AQAP, the Yemeni branch of al-Qaeda, has also been blamed for the foiled Christmas Day 2009 effort to bomb an airliner over Detroit and explosives-laden parcels that were intercepted the following year aboard cargo flights.
Seven suspected al-Qaeda militants were killed in two US drone air strikes in southern Yemen in June, officials say.
The piece of wreckage uncovered last week and believed to have come from one of the planes flown into the World Trade Center in the 9/11 attacks has been identified as a section of the wing, the NYPD has said.
The 5 ft piece was initially identified as a landing gear segment.
It was found by surveyors on Wednesday wedged in a narrow, rubbish-filled space 18 in wide.
Nearly 3,000 people died in the 9/11 attacks as hijackers brought down planes in New York, Washington and Pennsylvania.
Five suspected al-Qaeda militants are awaiting trial for the attacks at a military tribunal at the US detention facility in Guantanamo Bay, Cuba.
The plane part, known as a trailing edge flap actuation support structure, came from the underside of the wing, New York police said in a statement.
Authorities have not determined which of the two planes the metal piece came from.
The piece of wreckage uncovered last week and believed to have come from one of the planes flown into the World Trade Center in the 9/11 attacks has been identified as a section of the wing
The NYPDsecured the area in lower Manhattan – between 51 Park Place and 50 Murray Street – as a crime scene after the aircraft piece was found.
The location is at the site where a mosque and community centre has been proposed, three streets away from “Ground Zero” – where the twin towers once stood.
Police have taken photographs and are keeping the site off-limits until a health assessment has been made by the medical examiner’s office.
New York Police Commissioner Ray Kelly has said investigators would scour the space for possible human remains.
He said the piece of debris was found at about 11:00 local time on Wednesday by surveyors hired by the owner of 51 Park Place.
At 08:46 on 11 September 2001, American Airlines flight 11 hit the World Trade Center’s north tower. Seventeen minutes later, United flight 175 hit the south tower.
Although rubble from the attack was cleared in 2002, other debris has been found scattered across the area since.
Khalid Sheikh Mohammed is accused of masterminding the attacks while the other four men being held at Guantanamo Bay are accused of providing support for the co-ordinated hijacking.
They are charged with conspiring with al-Qaeda, terrorism, and one count of murder for each known victim of the 11 September attacks at the time the charges were filed – 2,976 in total.
The five face a possible death sentence if convicted.
The Oscar-nominated film tells the story of the hunt and killing of Osama Bin Laden. Screenwriter Mark Boal told the New York Times Betty Ann Ong was a “national hero”.
Betty Ann Ong, a flight attendant on American Airlines Flight 11, made a 23-minute phone call to authorities from an onboard phone to give them details of the hijacking.
She is among the victims whose voices are heard during a sequence at the start of Zero Dark Thirty. Her brother said the clip was used without permission.
“I thought it was just outrageous, and totally poor judgment, and an abuse of the voices,” Harry Ong told the New York Times.
The relatives of Betty Ann Ong, a flight attendant who died in the 9/11 attacks, have criticized the film Zero Dark Thirty for using a recording of her last call
Harry Ong has requested an apology be made at the Oscars if the film wins any of the five awards it is nominated for.
He also asked the film-makers to donate to a charitable foundation set up in Betty Ann Ong’s name, include a credit for her and put a statement on its website and DVD release making it clear that the Ong family did not endorse torture, which is depicted in the film.
Mark Boal told the newspaper: “As the 9/11 commission justly proclaimed, Betty Ong is without a doubt one of our national heroes.”
In a statement, film studio Sony and Annapurna Pictures said Mark Boal and director Kathryn Bigelow had been in close contact with the families of victims since releasing the film, which was privately screened for many of them.
“Zero Dark Thirty is, in some small way, a tribute to those forever affected by the attacks,” the statement said.
A link has now been added from the official Zero Dark Thirty website to the Betty Ann Ong foundation, the Voices of September 11th organization and the 9/11 memorial site.
The movie has been at the centre of much controversy since its release, including over its depiction of torture, the links between the film-makers and the CIA and whether it was a propaganda tool for President Barack Obama’s re-election.
Former US President George W. Bush was given a series of direct warnings throughout 2001 about the possibility of a terrorist attack by Al Qaeda – but failed to take them seriously, it was claimed today.
On the 11th anniversary of the 9/11 attacks, it has been reported that the White House received multiple briefs between May and August 2001 about an attack with explosives and numerous casualties.
But George W. Bush continually failed to take any significant action and questioned the thoroughness of the briefings – leading to huge frustrations within the CIA.
These repeated warnings came before the famous top secret briefing – which has previously been reported – given to George Bush on August 6 with the heading “Bin Laden Determined to Strike in the U.S.”.
Just a few weeks later on September 11, terrorists smashed planes into the World Trade Center in New York City – killing nearly 3,000 people and horrifying the world.
Details of the other briefings given to George W. Bush and his administration – which have never been made public – have now been revealed by The New York Times.
And they paint a startling picture of negligence at the heart of the U.S. government before 9/11.
The White House was made aware of potential attacks in the spring and, by May 1, was told by the CIA that “a group presently in the United States” was planning a terrorist attack, the Times reported.
In another daily brief on June 22, the administration was told that Al Qaeda strikes could be “imminent”.
President George W. Bush was given a series of direct warnings throughout 2001 about the possibility of a terrorist attack by Al Qaeda
However, the new neoconservative leaders at the Pentagon told the White House that the CIA had been fooled.
They believed that Osama Bin Laden was pretending to plan an attack to distract the U.S. from Iraqi leader Saddam Hussein.
Following this, the CIA prepared another daily brief for June 29 in which they listed over a page the evidence which they had built up.
This included an interview with a journalist from the Middle East in which aides of Bin Laden warned of an upcoming attack.
The briefing also included: “The U.S. is not the target of a disinformation campaign by Usama Bin Laden.”
It also included details from people close to Osama Bin Laden which claimed the expected attacks would have dramatic consequences with many casualties.
Another warning on July 1 said despite the attack being delayed it would soon take place.
But despite these warnings the White House did not appear to take them as seriously as the CIA was demanding.
The Times reports that officials within the CIA’s Counterterrorism Center became increasingly angry and in one meeting an official suggested the staff request a transfer so they could not be blamed when the attack occurred.
The White House was also told that the extremist Ibn Al-Khattab – known for his links to Al Qaeda – told his followers in Chechnya that there would “be big news soon”, the Times reported.
George W. Bush was told on July 24 that the attack was still being prepared but added that it had been postponed by a few months. However, he did not think the briefings were adequate and requested a much more detailed analysis of Al Qaeda.
This was to be the famous briefing of August 6 which was eventually declassified by the White House in April 2004 and made public.
“The administration’s reaction to what Mr. Bush was told in the weeks before that infamous briefing reflected significantly more negligence than has been disclosed,” Kurt Eichenwald wrote in the piece for the New York Times.
“In other words, the August 6 document, for all of the controversy it provoked, is not nearly as shocking as the briefs that came before it.”
Following the devastating attacks on 9/11, the White House – which was receiving criticism it had ignored CIA warnings – said it had never been told when or where the attacks would take place.
Yet many have claimed that if the government had been on high security alert over that summer they may have found out about the planned attack – and saved the lives of thousands.
Yet George Pataki, New York state governor on 9/11, laid into Eichenwald during a joint appearance on MSNBC for writing the New York Times article about the briefings.
“I just think this is incredibly unfortunate, to be perfectly honest. Because first of all, having been there, on September 11th and for weeks, months thereafter President Bush provided inspired, effective leadership,” George Pataki, a Republican, said.
“On September 11th everything changed and to look 11 years later and say, <<Aha, this was happening before September 11th in the summer>> and go though and selectively say, <<You should’ve done that, you should’ve done that>> I think is incredibly unfair and a disservice to history.
“And by the way if you look back there are those who could have said that President Roosevelt was at fault for Pearl Harbor. But the government didn’t look back and say, <<let’s blame the President>>; we came together to fight an important war.”
IGNORED WARNINGS: THE CIA BRIEFS ABOUT AL QAEDA ATTACK
May 1, 2001 CIA told White House that “a group presently in the United States” was planning a terrorist operation “with explosives”
June 22, 2001 CIA brief reported that Al Qaeda attacks could be “imminent”
June 29, 2001 Warning that the government needed to take briefs seriously. Added evidence included Osama Bin Laden aides warning of an attack and operatives claiming it would have “dramatic consequences”
July 1, 2001 Brief said the operation had been delayed but “will occur soon”
July 9, 2001 Extremist in Chechnya linked to Al Qaeda told followers there would soon be big news – and within 48 hours the information was passed to the White House
July 24, 2001 George W. Bush told the attack was still under preparation but that it had been postponed
August 6, 2001 George W. Bush received review of threats posed by Al Qaeda with headline: “Bin Laden Determined to Strike in U.S.”