A federal judge in California dealt a blow to President Trump’s plans for a signature border wall on Friday, barring the administration from diverting billions in military funds for construction.

The decision by US District Judge Haywood S. Gilliam of Oakland — the same judge who initially ordered a temporary injunction last month — can be appealed immediately.

It blocks the administration from tapping $2.5 billion in Department of Defense funds under a declaration of a national emergency — money that had not been approved by Congress.

Some $1.5 billion would have been transferred from military pay and training accounts into a Defense counterdrug program, something the judge said appeared to be illegal.

Such national emergency transfers apply only to “unforeseen needs,” the judge wrote, and Trump had demanded wall funding since his 2016 campaign.

With Associated Press