Final answer:
Following the 9/11 terrorist attacks, the U.S. enacted the Patriot Act to enhance surveillance for preventing terrorism, and established the Department of Homeland Security to coordinate security efforts.
Step-by-step explanation:
After the 9/11 terrorist attacks, the United States government implemented several significant policies to enhance national security and prevent future attacks. Two of the most notable policies were the Patriot Act and the creation of the Department of Homeland Security. The Patriot Act, passed shortly after the attacks, expanded the government's authority to monitor communications and gather information in an effort to detect and prevent terrorism. This act faced criticism over concerns of privacy and civil liberties. Meanwhile, the Homeland Security Act of 2002 led to the establishment of the Department of Homeland Security, which centralized various security functions and aimed to improve coordination among federal agencies.
These measures reflected a shift towards stronger federal power in response to the threats posed by international terrorism. The overhaul of national security infrastructure and policies marked a significant change in how the United States addressed both domestic safety and foreign threats in the post-9/11 era.