Attorney General Jeff Sessions announced a lawsuit against the state of California from the justice department over the state's sanctuary policies in numerous cities.
The suit targets policies that prohibit some cooperation with federal immigration enforcement.
Sessions slammed officials who he accused of promoting borders.
He singled out Oakland's mayor, who recently warned people ahead of federal immigration crackdowns.
Hundreds of suspected undocumented immigrants were arrested in those raids last week.
States and cities with sanctuary policies argue that they are protecting the interests of their residents.
