al-Qaeda
Middle-eastern terrorist coalition Al-Qaeda (then led by Osama Bin Laden) has since claimed responsibilities for the September 11th Attacks and Hijackings.
Al Qaeda, a terrorist group, has claimed responsibility for the September 11 attacks.
The terrorist group claiming accountability for 9/11 is al-Qaeda.
Al-Qaeda, led by Osama bin Laden, claimed responsibility for the September 11 attacks. The group had been planning and orchestrating the attacks for several years.
Al-Quaeda claimed responsibility for the attacks on 9/11.
It was uncertain who was responsible, though a previously unknown group calling itself the Deccan Mujahideen had contacted television stations to claim credit....Source- Economist
One way would be that Bin Laden himself (and his group) have publicly taken responsibility for the 9/11 attacks on the US and have publically taken responsibility for dozens of other terrorist attacks committed against other countries.
The Taliban is a terrorist group that was responsible for the 911 attacks.
Since the 9/11 Attacks, the prominent Islamic Extremist group Al-Qaeda has claimed responsibility.
Black Hand claimed responsibility for the assassination of the future king.
Al-Qaeda
The terrorist group Al-qaeda