New York: Khalid Shaikh Mohammed, the mastermind of the September 11 terror attacks on the United States continues to await trial even after two decades that left 2, 977 people dead.

19 terrorists of Al-Qaeda hijacked four commercial planes and carried out attacks in different locations in the USA. The hijackers crashed the first two planes into the twin towers of the World Trade Centre in New York City, and the third plane into the Pentagon (the headquarters of the American military) in Arlington, Virginia. The fourth plane was intended to hit a federal government building in Washington, DC, but crashed in a field.

Shaikh Mohammed was one of the most high-profile terrorists before he was captured from his hideout in Rawalpindi, Pakistan in March 2003 and later sent to Guantanamo Bay, Cuba to await trial, according to New York Post.

The terrorist has remained in Guantanamo Bay, Cuba ever since.

Condemning the US government's continued failure to avail justice to families of victims of the 9/11 attacks, a former US attorney in New York, David Kelley said, "It is an awful tragedy for the families of the victims," as he described the situation as a dent on country's history.

Notably, David Kelly co-chaired the Justice Department's nationwide investigation into the attacks, New York Post reported, adding that several victims' families say they just want closure.

George Haberman, the father of 25-year-old Andrea who got killed after one of the hijacked aeroplanes crashed into the World Trade Centre just one floor above her office, said that it is the need of the hour to unmask the truth about the incident and how it was done.

The FBI and its partners quickly learned that the 9/11 attacks were carried out by Osama bin Laden's terrorist organization. The 19 men who hijacked and crashed the four planes were all trained by al Qaeda, and bin Laden eventually admitted to his role in orchestrating the attacks.

The US began the war on terrorism by the invasion of Afghanistan. Other nations joined military operations in Afghanistan to find him and other al Qaeda terrorists. The US Navy SEALS killed Osama bin Laden on May 2, 2011, in a military operation at his location in Pakistan's Abbottabad.,

Ayman Al Zawahiri, was recently killed in a US drone strike in the Afghan capital Kabul in late July this year. The strike was conducted by the Central Intelligence Agency (CIA) and was carried out by an Air Force drone.

Zawahiri's killing comes a year after the US' military withdrawal from Afghanistan and the Taliban's takeover of the country.

Moreover, thousands of Americans who were infants or born after the 9/11 attacks joined the US military to combat terrorism in the US and also support democracy in Afghanistan including the 11 out of the 13 US service members killed in the dastardly bombing by the ISIS-K terrorists at the Kabul affiliate just days before the exit of the troops from the war-torn country.