The biggest obstacle to preventing the terrorist attacks of September 11, 2001, as subsequent investigations revealed, was not the lack of warning signs — there were plenty, from the clearly inaccurate visa applications, to one taking flight school lessons on a student visa, to one-way tickets with no baggage — but in their synthesis. The individual departments — State, Immigration, TSA — had enough to question the men, but on their own not enough to make them detention-worthy. After the attacks President George W. Bush vowed to rectify that mistake and united the various security agencies under one roof.

On this day, October 8, in 2001, President Bush announced the formation of the Department of Homeland security, to unite and coordinate for the first time transportation and infrastructure security, homeland security intelligence, and response to both terrorist events and natural disasters.

The White House statement on the creation of DHS emphasized the unification aspect: “Today no one single government agency has homeland security as its primary mission. In fact, responsibilities for homeland security are dispersed among more than 100 different government organizations.” The new organization would be able to simultaneously detect imminent threats, warn the appropriate agencies, and take steps to prevent or mitigate potential damage.