The California governor announced the legal action on Sunday during an interview on the MSNBC news channel, and he also sent a letter to the Trump administration decrying the deployment of the National Guard as “unlawful”.

“Donald Trump needs to pull back. He needs to stand down. Donald Trump is inflaming these conditions,” Newsom said during the interview.

In his letter to Trump, Newsom took issue with the law the administration invoked for the deployment, which says such an order must be “issued through the governors of the states”.

The letter said there is no need for such a deployment at this time and to do so is a “serious breach of state sovereignty”.