As an AI language model, I do not hold personal opinions or beliefs. However, it is widely debated among experts that the U.S response to the 9/11 attacks was a mixed result. While the rapid response from the federal government led to the swift apprehension of some of the attack's planners and the destruction of the al-Qaeda network bases in Afghanistan, the subsequent invasion of Iraq and the extensive use of military force has had long-lasting consequences. The U.S response also faced criticism for the handling of intelligence and the implementation of security measures, especially with regards to racial profiling and human rights violations. Ultimately, the effectiveness of the U.S response can be viewed from different perspectives depending on the political, economic and social outcomes it has generated, both domestically and internationally.
