New Delhi: As the world remembers 9/11 attack on its 18th anniversary, the flag at the US Embassy in New Delhi flew at half-mast today in honour of the victims and heroes of the 9/11 attacks.

‘Never forget 9/11’ was the sentiment on micro-blogging site Twitter to commemorate the 18th anniversary of the attack on New York’s World Trade Center.

The United Nations Security Council (UNSC) on Tuesday observed a moment of silence for victims of the 9/11 terrorist attacks in the United States 18 years ago.

“Seventeen years later, it hurts as much today as the day that it happened,” said US Ambassador to the United Nations Nikki Haley, who asked for a “point of personal privilege” at the beginning of a morning session of the Security Council, Xinhua news agency reported.

Haley, who presided over the meeting as President of the council for the month of September, asked for a moment of silence to remember the thousands of victims who lost their lives 18 years ago in New York City and Washington DC.

“That day taught us a lot of lessons. It taught us the lesson that we can never let our guard down; it taught us the lesson that the evil exists; it taught us the lesson that we should never stop trying for peace and security in this world,” Haley told the Security Council.

The US Army in a tweet said ‘We will never forget’ is more than a phrase. It is a testament of who we are as people and as a country.

“We will #neverforget the lives we lost on September 11, 2001, and we honor the service members who courageously answered the call to defend our Nation,” it said.

Several people took to Twitter to express their thoughts on the anniversary of 9/11 attack.

“This is what New York City looked like 18 years ago tonight on Monday September 10th, 2001. #NeverForget🇺🇸,” a user wrote.

“The Freedom Tower on the eve of 9/11. It’s been 18 years and we’re still here and not going anywhere. #NeverForget,” wrote another user.

Nearly 3,000 people were killed when four hijacked planes hit the World Trade Center Twin Towers in New York, the Pentagon near Washington and a field near Shanksville in Pennsylvania on September 11, 2001.

The 9/11 attack anniversary brings back haunting memories of the fateful day that “changed the world forever”.

A powerful explosion occurred near the US embassy in Kabul on Wednesday early morning. The explosion took place on the 18th anniversary of 9/11. Though no casualities have been reported, no group so far has claimed responsibility for the blast also.