The answer is the United States Department of Homeland Security. This cabinet department was established on November 25, 2002 by the Homeland Security Act of 2002. Its purpose involves anti-terrorism, cyber security, disaster prevention and management, border security, and immigration and customs. Overall, its responsibility is public security. It is the youngest cabinet and it was created in response to the September 11 attacks. In addition, it is the third largest cabinet department. The Homeland Security Council at the Whitehouse coordinates Homeland Security policies. The head of the Homeland Security Department is the Secretary of Homeland Security. The current Secretary of Homeland Security under President Donald Trump is Kirstjen Nielsen of Florida. She has been serving since December 5, 2017.