Washington, D.C., and Virginia sued the National Park Service and Interior Department on Saturday in a last-minute bid to stop construction on President Donald Trump’s proposed 250-foot triumphal arch. The Trump Administration has said that construction could begin as early as next week.

The new challenge joins two existing lawsuits against the arch, adding to a series of legal battles testing the limits of Trump’s authority to remake Washington.

Calling the project “flagrantly unlawful,” the lawsuit points to the Commemorative Works Act, which requires Congressional authorization for memorials on federal land in Washington and its environs. The lawsuit also alleges violations of the Administrative Procedure Act, the National Environmental Policy Act, and the National Historic Preservation Act, arguing that the Administration failed to adequately assess the project’s effects and consult as required.

“In their rush to break ground on the Arch, Defendants have made only half-hearted gestures at complying with these requirements,” the lawsuit filed Virginia Attorney General Jay Jones and D.C. Attorney General Brian L. Schwalb, claims. “Perhaps recognizing that the project is legally indefensible, Defendants have made clear that they will attempt to outrun judicial review.”

“The Commonwealth has a solemn duty and a profound interest in preserving the dignity of this sacred place,” Jones said in a statement to the Washington Post. “We will vigorously litigate to protect its sanctity and honor the legacy of those who made the ultimate sacrifice.”

The Administration argued in a June 17 filing for Lemmon v. Trump—a separate suit filed in February—that Congress already authorized construction at the site in 1925, when it approved plans for Arlington Memorial Bridge that included two monumental columns. Those columns were never built.

In Lemmon, three Vietnam War veterans and an architectural historian argue that the arch would “block historically significant reciprocal views between” the Lincoln Memorial and Arlington National Cemetery. The plaintiffs have also argued that the plan requires congressional authorization.

The Arlington County Board then filed its own suit Oct. 8 arguing that the construction would disrupt roads important to emergency services and “significantly and detrimentally” affect Arlington National Cemetery.

In response to those suits, and defending the urgency of the project, Trump announced last month that he had agreed, at the Defense Department’s request, to incorporate a military complex into the planned arch, including facilities for drones and snipers.

In sworn declarations filed Oct. 28, Defense Secretary Pete Hegseth and Homeland Security Secretary Markwayne Mullin reiterated the claim that the arch is central to national security.

“The arch is a generational national defense opportunity to mitigate these evolving threats,” Hegseth wrote in his declaration.

The National Capital Planning Commission (NCPC), a federal review panel, is scheduled to consider final approval of the arch’s site and building plans on Nov. 5. The commission includes several Trump appointees, and its chairman has said he plans to support the project, according to the Washington Post.

Interior must also issue its final authorization and publish the required notice. The Administration has told the court that those steps could be completed on Nov. 5, as well, allowing construction to begin that same day. The Justice Department told the court on Friday that construction could begin immediately once those steps were complete.

U.S. District Judge Tanya Chutkan, however, seemed skeptical of the rush.

“What’s the harm to the government to wait 3 or 4 months? What’s the rush to put this arch up?” the judge asked at the hearing for Lemmon v. Trump on Friday.

Chutkan observed that the issue was complex. She said that she would consider the plaintiffs' standing over the weekend and rule expeditiously. TIME has reached out to the White House about the new lawsuit. What Could These Lawsuits Mean for Trump's Other Renovation Projects?

The triumphal arch is just one of several projects that Trump has introduced in his second term to remake Washington in his image, including the demolition of the White House East Wing and construction of a White House ballroom, the planned 15-month closure and massive overhaul of the historic East Potomac golf course, and plans to restore and rename the Kennedy Center.

In Friday’s hearing, Deputy Assistant Attorney General Robert Stander cited the Supreme Court’s 5-4 decision in August allowing ballroom construction to continue while litigation proceeded. The majority said the Administration was likely to prevail in arguing that the preservation group had not demonstrated the concrete harm needed to sue. “It’s the same thing,” Stander said. Chutkan, however, said that the two legal battles remain distinct in nature.

“The ballroom case differs in significant respects,” she said, pointing to traffic and public safety concerns from plaintiffs in the case.

Chutkan also raised skepticism around the Administration’s justification of national security and pointed out how when Trump announced the arch, its purpose was initially posited as celebrating the country’s 250th anniversary. “This is the first time the government has proffered a national security aspect to this case,” she said.

The arch dispute adds to a broader debate over the Administration’s frequent use of national security to justify its policies.

Beyond defending the White House ballroom and triumphal arch on national security grounds, the Trump Administration has invoked national security to justify pausing offshore wind development, barring journalists from CNN, MS NOW, and Politico from the White House, and exempting oil and gas activities in the Gulf of Mexico from certain Endangered Species Act requirements.

The golf-course litigation raises a related question about congressional authority: Plaintiffs there have also argued that federal law requires Congress’s express authorization to erect structures on federal public grounds in Washington. For now, the immediate question is whether a court will intervene before construction can begin as early as the coming week.