Job of homeland security secretary is to adapt almost continuously to pressures from the department, the public and the world at large

The secretary of homeland security is the newest permanent member of the president’s Cabinet, overseeing the sprawling agencies and missions of the U.S. Department of Homeland Security and an annual budget exceeding US$62.2 billion.

Overall, the department – and the secretary who leads it – is charged with protecting the nation from all hazards. The department must respond to natural disasters, screen millions of aviation passengers a day, protect the president and other senior national leaders, fight domestic and international hackers, protect dams, power plants and other critical systems across the country, ensure border security and enforce immigration laws.

It is a massive bureaucracy with many critical national security functions.