President Donald Trump moved Thursday to end collective bargaining with federal labor unions in agencies with national security missions across the federal government, citing authority granted him under a 1978 law.

The order, signed without public fanfare and announced late Thursday, appears to touch most of the federal government. Affected agencies include the Departments of State, Defense, Veterans Affairs, Energy, Health and Human Services, Treasury, Justice and Commerce and the part of Homeland Security responsible for border security.

Police and firefighters will continue to collectively bargain.

Trump said the Civil Service Reform Act of 1978 gives him the authority to end collective bargaining with federal unions in these agencies because of their role in safeguarding national security.

The American Federation of Government Employees, which represents 820,000 federal and D.C. government workers, said late Thursday that it is “preparing immediate legal action and will fight relentlessly to protect our rights, our members, and all working Americans from these unprecedented attacks.”

“President Trump’s latest executive order is a disgraceful and retaliatory attack on the rights of hundreds of thousands of patriotic American civil servants — nearly one-third of whom are veterans — simply because they are members of a union that stands up to his harmful policies,” AFGE National President Everett Kelley said.

AFL-CIO President Liz Shuler said in a statement, “It’s clear that this order is punishment for unions who are leading the fight against the administration’s illegal actions in court — and a blatant attempt to silence us.” She also vowed, “We will fight this outrageous attack on our members with every fiber of our collective being.”

The announcement builds on previous moves by the Trump administration to erode collective bargaining rights in the government.

Earlier this month, DHS said it was ending the collective bargaining agreement with the tens of thousands of frontline employees at the Transportation Security Administration. The TSA union called it an “unprovoked attack” and vowed to fight it.

A White House fact sheet on Thursday’s announcement says that “Certain Federal unions have declared war on President Trump’s agenda” and that Trump “refuses to let union obstruction interfere with his efforts to protect Americans and our national interests.”

“President Trump supports constructive partnerships with unions who work with him; he will not tolerate mass obstruction that jeopardizes his ability to manage agencies with vital national security missions,” the White House said.