Final answer:
The operation that focused on protecting the US homeland from similar attacks as those on September 11 was the creation of the Office of Homeland Security, the Transportation Security Administration, the Homeland Security Act that led to the Department of Homeland Security, and the USA Patriot Act.
Step-by-step explanation:
Operation Protecting the US Homeland Post-9/11
The operation that focused on protecting the US homeland from internal and external air attacks of the nature used on September 11 was the establishment of the Office of Homeland Security in October 2001. Following the terrorist attacks, President Bush acted to strengthen domestic security amid concerns of further terrorist strikes. By December 2001, this initial response evolved into a more formal structure with the creation of the Transportation Security Administration (TSA), whose core responsibilities included securing the transportation systems within the United States, particularly air travel. Additionally, in 2002, the Homeland Security Act was passed by Congress, resulting in the formation of the Department of Homeland Security (DHS), consolidating several federal agencies to better manage and mitigate threats to the homeland.
Moreover, the USA Patriot Act was passed, expanding the abilities of law enforcement agencies to surveil and intervene in suspected terrorist activities, including enhanced monitoring of phone and email communications without the need to obtain a traditional warrant. These efforts were part of the broader War on Terror which included military campaigns abroad, but these particular operations were directly focused on bolstering security within the United States.