principal missions principal missions 22 then-existing entities DHS History principal missions principal missions 22 then-existing entities principal missions 22 then-existing entities principal missions Department of Homeland Security 22 then-existing entities https://www.dhs.gov/history Department of Homeland Security Department of Homeland Security 22 then-existing entities 22 then-existing entities 22 then-existing entities website dhs.gov principal missions http://www.dhs.gov/history 22 then-existing entities 22 then-existing entities History 22 then-existing entities principal missions History