<P> In January 2003, the office was merged into the Department of Homeland Security and the White House Homeland Security Council, both of which were created by the Homeland Security Act of 2002 . The Homeland Security Council, similar in nature to the National Security Council, retains a policy coordination and advisory role and is led by the Assistant to the President for Homeland Security . </P> <P> As of January 13, 2011, the DHS advised the American public of an' elevated national threat' level, recommending that all Americans' should establish an emergency preparedness kit and emergency plan for themselves and their family, and stay informed about what to do during an emergency' . </P> <P> In response to the September 11 attacks, President George W. Bush announced the establishment of the Office of Homeland Security (OHS) to coordinate "homeland security" efforts . The office was headed by former Pennsylvania Governor Tom Ridge, who assumed the title of Assistant to the President for Homeland Security . The official announcement stated: </P> <Table> <Tr> <Td> "</Td> <Td> The mission of the Office will be to develop and coordinate the implementation of a comprehensive national strategy to secure the United States from terrorist threats or attacks . The Office will coordinate the executive branch's efforts to detect, prepare for, prevent, protect against, respond to, and recover from terrorist attacks within the United States . </Td> <Td>" </Td> </Tr> </Table>

The largest investigative arm of the department of homeland security is known as