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.

The order targets agencies it says have a national security mission but many of the departments don’t have a strict national security connection.

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.