Frances Townsend, former chief anti-terrorism and homeland-security adviser to President George W. Bush, joined CNN as an on-air contributor.
She will provide analysis on national-security issues for the network.
She also formerly worked in the Justice Department under the Clinton administration.
She was chair of the Homeland Security Council from May 2004 until exiting in January. Before that, she was deputy national security adviser for combating terrorism.
Townsend said she will talk about "how serious the threat [of global terrorism] is, what is being done about it and how much is left to do."