Two dozen state attorneys general are asking the Trump administration to crack down on Defense Distributed’s Defcad site for selling 3D-printed gun files. In a letter sent today, they urged the Justice Department and State Department to enforce rules against exporting weapons and making undetectable firearms. “If the federal government fails to act, these files will be distributed widely with potentially grave consequences for our national and domestic security,” warns the letter.

Attorneys general argue that Defcad is violating export control regulations and the Undetectable Firearms Act, which bans manufacturing, owning, and selling guns that don’t trigger metal detectors. Anyone who downloads files could “automatically manufacture functional weapons that cannot be detected by a standard metal detector and, furthermore, are untraceable because they lack serial numbers,” says the letter. “Continued dissemination of these files will increase the risk of terrorist attacks and gun violence across the United States.”

Defcad has made several false starts, especially under the Obama administration, which contended that publishing printable weapon files violated International Traffic in Arms Regulations (ITAR). The Trump administration reversed course and settled with Defense Distributed, but state attorneys general filed a lawsuit, and a federal judge blocked its decision multiple times. Despite this, Defcad launched in March with a vetting system to allow only US residents, a strategy it claimed was “impervious” to legal challenge — although it acknowledged a buyer could redistribute the files to other people.

Defcad has well-established problems with ITAR, but the letter doesn’t explain how it violates the Undetectable Firearms Act beyond asserting that files “enable the automatic manufacture of functional plastic weapons.” While lawmakers have proposed updates to expressly ban 3D-printed plastic weapons, they’ve focused on the act of making the guns rather than distributing the plans.