President Donald Trump took his most consequential action against federal employee unions yet late Thursday, signing an executive order aimed at ending collective bargaining for government employees whose work include national security aspects.

President Donald Trump is ending 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 White House singled out WilmerHale as it ramps up its campaign against firms connected to individuals perceived as political enemies by the president.

Donald Trump on Thursday signed yet another executive order targeting a law firm linked to attorneys who have investigated him. The order against WilmerHale contained some of the same provisions that Trump previously used on other firms, like the cancellation of government contracts and the suspension of its employees’ security clearances.

The discussions come as President Trump has taken aim at Wilmer Hale, another big law firm. Other major firms are said to be trying to cut deals with the White House.