A federal judge on Thursday blocked above-ground construction of a planned $400 million White House ballroom, ruling that the Trump administration’s claim that the entire project qualifies as a national security measure is “neither a reasonable nor a correct” reading of his earlier order. U.S. District Judge Richard Leon said that below-ground work on a bunker and other security facilities at the site may continue, but that the ballroom’s surface structure may not.

The ruling is the latest setback in a legal battle over the Trump administration’s plan to build a 90,000-square-foot ballroom on the site of the demolished White House East Wing — a project that has drawn challenges from historic preservation groups and from Congress, where members have argued that construction requires legislative approval.

U.S. District Judge Richard Leon on Thursday blocked above-ground construction of a planned $400 million White House ballroom, ruling that the Trump administration’s claim that the entire project qualifies as a national security measure is “neither a reasonable nor a correct” reading of his earlier order.

Leon, nominated to the federal bench by Republican President George W. Bush, said that below-ground work on a bunker and other security facilities at the site may continue, but that the ballroom’s surface structure may not. The ruling came in response to a directive from a three-judge panel of the U.S. Court of Appeals for the District of Columbia Circuit, which had said it lacked sufficient information to determine how much of the project could be paused without endangering White House security.

Trump responded on social media by calling Leon a “Trump Hating” judge who “has gone out of his way to undermine National Security, and to make sure that this Great Gift to America gets delayed, or doesn’t get built.” The administration filed notice that it will ask the D.C. Circuit to review Leon’s latest decision.

The dispute over national security

Government lawyers had argued the project includes critical security features guarding against a range of threats — including drones, ballistic missiles, and biohazards — and that the construction therefore qualifies entirely as exempt from Leon’s injunction. The judge rejected that argument.

“Defendants argue that the entire ballroom construction project, from tip to tail, falls within the safety-and-security exception and therefore may proceed unabated,” Leon wrote. “That is neither a reasonable nor a correct reading of my Order!”

Leon said he recognizes the safety implications of the case but stressed that “national security is not a blank check to proceed with otherwise unlawful activity.” He also wrote that he has “no desire or intention to be dragooned into the role of construction manager.”

Leon stayed his latest decision for one week, giving the administration additional time to seek review from the Supreme Court.

The ballroom is planned for the 90,000-square-foot site where the White House East Wing stood before its demolition. Trump has said the project, designed to hold 999 people, is funded by private donations. Public money is paying for the bunker construction and security upgrades.

The National Trust for Historic Preservation sued in December after the White House demolished the East Wing. Carol Quillen, the organization’s president and chief executive, said in a statement that the group is pleased with Thursday’s ruling.

Leon’s March 31 order barred above-ground work on the ballroom unless Congress approved it, while exempting construction necessary to ensure White House safety and security. He said he reviewed material the government submitted privately before concluding that halting construction would not jeopardize national security. Leon had suspended that March 31 order for two weeks before issuing Thursday’s ruling.

On April 2, the 12-member National Capital Planning Commission, which is charged with approving construction on federal property in the Washington region, gave the ballroom project its final regulatory approval.