Final answer:
Challenges of the war on terror include transnational threats, intelligence failures preceding 9/11, absence of WMDs in Iraq, and controversial treatment of prisoners. These have hindered legitimacy and possibly aided enemy recruitment.
Step-by-step explanation:
The continued efforts of the war on terror have faced numerous challenges. One major problem has been the prevalence of transnational threats, with terrorist groups not confined to a single state, thus requiring more intelligence-gathering and military precision than traditional diplomatic methods. The 2004 report by the 9/11 Commission indicated failures by the Clinton and Bush administrations in addressing credible threats prior to the attacks and refuted a meaningful connection between Al Qaeda and Iraq.
Furthermore, the lack of weapons of mass destruction (WMDs) in Iraq, contrary to initial claims, undermined the war's legitimacy. The surge of U.S. forces in Iraq and the treatment of prisoners, such as in Guantanamo Bay and Abu Ghraib, further tarnished the U.S. image and raised fears that these actions served to recruit more individuals to terrorist causes. The need for multilateral cooperation versus unilateral actions has been an ongoing debate, with the U.S. often choosing to act independently.