More than two decades after the Homeland Security Department was created, former secretaries Michael Chertoff and Jeh Johnson say it has strayed from its core mission.

Former DHS secretary says U.S. safer now than before 9/11, agency has largely successfully evolved with emerging threats.

More than two decades after the Homeland Security Department was created, former secretaries Michael Chertoff and Jeh Johnson say it has strayed from its core mission.