Final answer:
The FBI has primary responsibility for terrorism investigations at the national level, which is true. This role is part of the broad federal efforts to protect the nation from terrorist threats, bolstered by initiatives such as the establishment of the Department of Homeland Security and programs like the Terrorist Surveillance Program.
Step-by-step explanation:
The statement "At the national level, the FBI has primary responsibility for terrorism investigations" is true. The Federal Bureau of Investigation (FBI), which is the chief federal law enforcement agency within the United States, takes a significant role in domestic anti-terrorism efforts. Alongside other federal entities like the Department of Homeland Security (DHS) that was created after the 9/11 attacks, the FBI operates under its jurisdiction to prevent and respond to terroristic activities.
While the FBI's activities are constitutionally limited, as citizens are protected against unreasonable searches and seizures by the Fourth Amendment, there have been broader measures in recent history, such as the warrantless domestic wiretapping known as the Terrorist Surveillance Program by the National Security Agency (NSA), which was later challenged in court. Additionally, following the 9/11 attacks, the federal government has conducted various operations to safeguard the country against foreign and domestic terrorist threats, illustrating the FBI's central role in such investigations.