() A federal judge ruled President Donald Trump’s use of the National Guard to fight crime in California is illegal and blocked the president from continuing to deploy those troops.

The ruling has been put on hold until Sept. 12.

Judge Charles Breyer ruled that the deployment violated the Posse Commitatus Act, which prohibits the use of military force for domestic law enforcement without the authorization of Congress.

Trump federalized California’s National Guard and sent 4,000 troops and 700 active-duty Marine to Los Angeles after protests broke out in response to immigration raids.

Breyer said in his opinion, the administraiton used troops for crowd control, setting up periumeters and blocking traffic.

The Trump adminstration responded by arguing that they were using the troops to protect federal personnel, which is an exception to the Posse Commitatus Act.

Trump has also deployed the National Guard in Washington, D.C., to fight crime, through the use of Home Rule, which gives the government more authority to act in the district, which does not have statehood.

He has also threatened to deploy National Guard troops in other Democratic-run cities to fight crime despite objections from local leaders.

Trump has suggested Chicago, Baltimore, New York and San Francisco could see the use of National Guard and federal agents, which the president claims is necessary to crack down on crime.

The Trump administration is likely to appeal the ruling.