President Donald Trump attacked a nonprofit group, accusing it of treason after it sued to stop construction of a new White House ballroom, according to a post he shared on Truth Social. The lawsuit, brought by the National Trust for Historic Preservation against the Trump administration, ended in the nonprofit’s favor last week when a federal court determined the ballroom project couldn’t move forward without congressional approval and ordered construction paused until that sign-off is secured. According to Mediaite, the National Trust describes itself as a privately funded nonprofit that has worked to protect America’s historic sites for more than 75 years. Construction on the ballroom began last year, on the spot where the White House East Wing once stood before Trump had it torn down. Trump questions the group’s name and funding history In his post, Trump called the National Trust “TREASONISTS” and claimed the group had exposed top military secrets. He also disputed the legitimacy of the organization’s name. “‘The National Trust for Historic Preservation’ is a beautiful name, but even their name is fake because when they add the words ‘in the United States’ to the National Trust for Historic Preservation, it makes it sound like a Governmental Agency, which it is not,” Trump wrote.’ Trump Blasts ‘TREASONISTS’ Behind Ballroom Case In Late-Night Rant After Asking For Supreme Court Interventionhttps://t.co/8oFAjsvduP pic.twitter.com/jHSrKq5Wjk— Forbes (@Forbes) August 15, 2026 Trump said the federal government stopped funding the group in 2005 because officials disagreed with its mission. He claimed the group blocks many worthwhile projects and causes harm as a result. He also repeated his claim that the ballroom project is critical to national security. Trump said the building would protect current and future presidents, their families, staff, and Cabinet members. He claimed the military had asked the National Trust not to file the lawsuit because the facility involved secret information, and that top military and Secret Service officials had shown the group detailed plans of what he called a “knitted, unified, and cohesive structure.” Trump said the group ignored these warnings because it suffers from “Trump Derangement Syndrome.” He credited Pennsylvania Senator John Fetterman, a Democrat, with coining that term. Trump added that the ballroom’s lower and upper sections depend on each other structurally, calling the project “all one highly integrated unit.” Trump also criticized Carol Quillen, the former president of the National Trust who brought the lawsuit. He said she had no background in historic preservation and had been removed from her position. He compared this to what he described as her earlier departure from Davidson College, though he did not provide details on that claim. Trump argued that Quillen was responsible for revealing secret military features of the building, including what he called the “DronePort,” which he said covers the entire roof. Trump also addressed a woman who reportedly walks her dog near the White House and was involved in the case. He questioned whether she had legal standing to be part of the lawsuit, noting that she had not seen the building because it had not yet been constructed when the case began. He described her as “an activist, or serial plaintiff” involved in other lawsuits around the city, though he did not name her or provide evidence for this description. He said she lacked security clearances or expertise related to national defense or presidential protection, and pointed out that she was not formally listed as a plaintiff in the case. The project has faced multiple legal hurdles before too, such as when a court blocked construction of the White House ballroom. Trump argued that allowing such lawsuits to proceed damages public trust in the legal system, writing, “It is this kind of gross and flagrant abuse of our Courts that is exactly why Americans are losing faith in our System of Justice.” The ballroom has drawn scrutiny from Trump before. Last year, he clashed with architect James McCrery II over the size of the structure. McCrery reportedly told Trump he was concerned that the ballroom, planned at 90,000 square feet, would be larger than the White House itself, which measures about 55,000 square feet. Trump reportedly pushed McCrery off the project in December, though the White House disputed that he was fired, saying he’d stay on as a consultant. Despite the legal setbacks, some of the president’s supporters have gone as far as framing the ballroom as a divine mission. Trump has said no taxpayer money would fund the ballroom, claiming it would be paid for entirely through private donations. However, the project’s estimated cost has grown over time and now stands at about $600 million. According to invoices reviewed by The Washington Post, roughly half of that cost is being paid by taxpayers rather than private donors.