Former Pennsylvania governor Mr Tom Ridge today formally took the helm of the fledgling US Department of Homeland Security, tasked with thwarting terrorist attacks like those of September 11th, 2001.
"We're taking every measure to protect the American people against a serious and ongoing threat," said US President George W. Bush, who presided as vice-president Dick Cheney administered the oath of office to Mr Ridge.
"The Department of Homeland Security will lead a comprehensive and unified effort to defend this nation," said Mr Bush, who had tapped his old friend to head the White House's Office of Homeland Security shortly after the 2001 strikes.
The moderate Republican, who won unanimous Senate confirmation on Wednesday, was flanked by his wife, Michele, son Tommy and daughter Lesley at the brief ceremony.
The new, cabinet-level department - the fruit of the largest reorganization of the US government since the 1947 creation of the Defense Department - groups 22 federal agencies and 170,000 employees.
It will integrate traditionally separate efforts by the Coast Guard, the Immigration and Naturalization Service, the Customs Service and other federal agencies, as well as the newly formed Transportation Security Administration that is charged with air travel safety.
Critics have said the new department will do little to enhance the government's ability to thwart future terrorist attacks, noting that the reorganization will not affect the CIA or FBI.