Final answer:
The impact of Al-Qaeda has been due to both missed opportunities by the US to counter them and strategic blunders, such as the redirection of military efforts from Afghanistan to Iraq based on incorrect intelligence. Al-Qaeda's ongoing terror campaigns also demonstrate their continued influence.
Step-by-step explanation:
Al-Qaeda's ability to be impactful has stemmed from various factors, including political, historical, and military contexts.
The group, led by the militant Osama bin Laden, claimed to wage a "jihad" or holy war against the West and the United States. Their impact was particularly felt after the September 11 attacks in 2001, which drew international attention and led to major geopolitical shifts.
The 9/11 Commission reported that Al-Qaeda was able to plan the September 11 attacks partly because of the missed opportunities for the US intelligence and defense apparatus to respond to credible reports of an impending attack.
Additionally, the absence of weapons of mass destruction (WMDs) in Iraq, after claims had been made to that effect, alongside the news of US military casualties, affected the perception of the US-led war on terror.
Conflicting interests and the shifting of military focus from Afghanistan to Iraq also allowed Al-Qaeda and associated movements like the Taliban to persist instead of being eliminated.
The claim that there was a meaningful connection between Al-Qaeda and Iraq was refuted, and the resources that could have potentially captured bin Laden earlier were redeployed to Iraq, under the mistaken belief that Saddam Hussein was connected to Al-Qaeda and possessed WMDs.
This strategic decision impacted the efficiency of US efforts against Al-Qaeda in Afghanistan.
Subsequent interventions and lack of stability in regions like Somalia were seen by some as lost opportunities to foster goodwill in the Muslim world, potentially giving groups like Al-Qaeda more leverage and support.
Furthermore, groups affiliated with Al-Qaeda, such as Al-Qaeda in the Lands of the Islamic Maghreb, have continued campaigns of terror, showing the ongoing influence and reach of the network.