Gov. Gavin Newsom’s office, in a letter to the Trump administration, called the deployment of troops “unlawful” and a “serious breach of state sovereignty.”

Tear gas and smoke have filled the air on the southern outskirts of Los Angeles as confrontations between immigration authorities and demonstrators extended into a second day.

Defying California Gov. Gavin Newsom, President Donald Trump ordered 2,000 National Guard troops to Los Angeles following a second consecutive day of...