Twenty U.S. states sued the Trump administration on Thursday to block what they called its latest effort to allow blueprints for making guns from 3D printers to be released on the internet, threatening a proliferation of "ghost guns" that spread violence.

Led by Washington state and controlled primarily by Democrats, the states, along with the District of Columbia, said they sued in federal court in Seattle, after the government published final agency rules earlier in the day allowing the necessary files to be posted.

According to the states, the new rules transfer oversight of 3D printed guns to the Commerce Department from the State Department, effectively ending Congressional oversight of the blueprints and leaving behind a loophole-filled regulatory scheme allowing their distribution "with ease."