Napolitano acknowledged that increased security would mean sacrificing individual liberties in some instances, but said those disruptions can be minimized.

"We can significantly advance security without having a deleterious impact on individual rights in most instances," Napolitano said. "At the same time, there are situations where trade-offs are inevitable."

One example she cited was the use of full-body scanners at airports, which some privacy advocates have deemed invasive. Napolitano said the Transportation Security Agency has mitigated the risks to travelers' privacy by banning operators from saving scans or taking pictures of them to preserve them for later.

Stewart Baker, former Department of Homeland Security Assistant Secretary for policy under President Bush, told the Associated Press that Napolitano's comments show the Obama administration has matured in its understanding of how to best combat terrorism.

"Her speech is sign of the maturing of the administration on this issue," Baker said. "They now appreciate the risks and the trade-offs much more clearly than when they first arrived, and to their credit, they've adjusted their preconceptions."