New York, Sep 12 : With pledges to defend the nation and freedom, the US remembered the horrific attack on the US 24 years ago by Islamic terrorists whose leader found a welcome in Pakistan.

"We will build taller, grow stronger, fight harder, and soar higher. And together, we will go forward as one people with one heart, one fate, one flag, and one glorious destiny under one Almighty God," US President Donald Trump said on Thursday.

"We will defend the nation they served, the values they upheld, and the freedom for which they died," he said, referring to the victims and the first responders, thousands of whom face serious health issues from the toxic fumes stirred by the burning debris.

Ironically, the remembrances of the 9/11 al-Qaeda terrorist attack were held under the shadow of domestic terrorism that took the life of a conservative political activist close to Trump, Charlie Kirk, on Wednesday.

Trump's remembrance ceremony at the Pentagon ' one of the three places scarred by 9/11 terrorism - was itself tinged by that terrorist act and moved inside the defence headquarters complex from the traditional spot at its entrance because of its vulnerability.

"On that fateful day, savage monsters attacked the very symbols of our civilisation. Yet, here in Virginia , and in New York, and in the skies over Pennsylvania, Americans did not hesitate," he said, recalling the national unity in the 9/11 aftermath in contrast to its fraying seen in the week's political violence.

"Today, as one nation, we renew our sacred vow that we will never forget September 11, 2001," he said.

At ceremonies held at the three spots where the terrorists struck, bells tolled the time of the attack and the names of the 2,977 were solemnly intoned.

People of Indian origin, estimated at 250, of whom 32 were born in India, were among the victims.

Across the nation, commemorations were also held at the memorials to the victims of the attack that has been seared into the nation's psyche.

On 9/11, 19 hijackers belonging to al-Qaeda hijacked four passenger planes, two of which were crashed into the twin towers of the World Trade Centre in New York.

Another was weaponised against the Pentagon, but the passengers heroically overpowered the hijackers, forcing the plane to crash into a field in Pennsylvania before it could hit their intended target in Washington.

Osama bin Laden, the dreaded leader of al-Qaeda behind the attacks, was welcomed by Pakistan, where the US exacted its vengeance by hunting him down and killing him near a military establishment.

At Ground Zero in Manhattan, Federal Bureau of Investigation Director Kash Patel attended the ceremony before heading out to Utah to oversee the investigation into the assassination of Kirk.

/IANS