New York: The United States is marking 25 years since the September 11, 2001 terrorist attacks, with families, survivors, first responders and officials gathering at the three places targeted in the attacks to remember the 2,977 people who were killed.
Ceremonies are taking place in New York, at the Pentagon in Virginia and near Shanksville, Pennsylvania, where United Airlines Flight 93 crashed after passengers fought back against the hijackers.
In New York, family members are reading the names of the victims at the 9/11 Memorial at the World Trade Center site. The ceremony began at 8:30 a.m., with the first moment of silence at 8:46 a.m., the time when the first hijacked plane struck the North Tower.
This year's ceremony has a significant change. For the first time, there are seven moments of silence. The seventh honours people who later died from illnesses and injuries linked to exposure after the September 11 attacks.
President Donald Trump is attending the commemoration at the Pentagon, while Vice President JD Vance is attending the ceremony in New York. Officials and families are also gathering at the Flight 93 memorial in Pennsylvania.
The attacks began on the morning of September 11, 2001, when 19 al Qaeda hijackers seized four commercial aircraft.
American Airlines Flight 11 struck the North Tower of the World Trade Center at about 8:46 a.m. United Airlines Flight 175 hit the South Tower at about 9:03 a.m. American Airlines Flight 77 struck the Pentagon at about 9:37 a.m. Flight 93 crashed near Shanksville at about 10:03 a.m.
The attacks killed 2,977 people, excluding the 19 hijackers. The victims came from more than 90 countries.
A quarter of a century later, the consequences continue to be felt.
The federal World Trade Center Health Program says more than 96,000 people have been diagnosed with physical or mental health conditions linked to exposure to dust, smoke, debris and other conditions following the attacks.
The continuing health impact is reflected in this year's seventh moment of silence, which honours people who died from illnesses and injuries connected to the aftermath of September 11.
The anniversary is also bringing renewed attention to records about the government's response to the disaster.
New York City released about 170,000 pages of records earlier this week relating to the city's response to September 11, including documents concerning air quality and health issues. City officials say additional records will be released during the next year.
The significance of the newly released material remains subject to further examination. The records have renewed questions about what government agencies knew about conditions around Ground Zero and when they knew it.
The attacks transformed US foreign and security policy. They led to the US war in Afghanistan and were followed by the 2003 US led invasion of Iraq. The attacks also brought major changes to aviation security, surveillance and intelligence gathering.
The international consequences were also significant. NATO invoked Article 5 for the first and only time in its history after the attacks, treating the assault on the United States as an attack on the alliance as a whole.
Al Qaeda has changed considerably since 2001. Its founder Osama bin Laden was killed by US forces in Pakistan in 2011, while his successor Ayman al Zawahiri was killed in a US strike in 2022.
The organisation's central leadership is weaker than it was in 2001, but its affiliates remain active in several regions.
British intelligence chief Ken McCallum has warned that governments must also prepare for threats that may look very different from those seen in the past.
Justice for the attacks also remains unfinished.
Khalid Sheikh Mohammed, who is accused of being the mastermind of the attacks, remains held at Guantanamo Bay, Cuba. A military judge has scheduled his trial, along with three co defendants, for June 5, 2028.
The case has faced years of delays, and further postponement remains possible.
The anniversary is also becoming increasingly important for a generation that did not experience the attacks directly. The 9/11 Memorial and Museum estimates that about 100 million Americans are now too young to remember what happened that day.
For those who lived through September 11, the memories remain personal. For younger people, the attacks are increasingly part of history taught through families, schools, museums and public ceremonies.
Twenty five years after the attacks, the annual remembrance is about more than looking back at one terrible morning. It is also about the lives lost, the people who became ill, the wars and security policies that followed, the unresolved legal cases and the changing way the event is remembered.