"We will not stand for the evasion, especially the flouting, of current law and will take action to ensure that individuals who violate the law by making plastic firearms and rendering them undetectable, will be prosecuted to the fullest extent," Sessions said on Thursday.
Earlier in the day, Washington State Attorney General Bob Ferguson criticized President Donald Trump for continuing to take steps to make 3D printed guns widely available despite public remarks to the contrary.
The Trump administration on Wednesday filed a legal brief opposing a court ruling that has temporarily blocked the publication of instructions on how to make 3D printed guns.
On July 31, a federal judge issued a temporary restraining order blocking the private company Defense Distributed from sharing gun blueprints online. The ruling came in response to a lawsuit filed by Washington and several other US states to prevent the deregulation of "ghost guns."
In 2015, Defense Distributed filed a lawsuit after the State Department, citing international arms control regulations, forced the removal of its instruction manuals from the Internet. The organization later reached a settlement with the government that allowed them to move forward with plans for distributing gun designs online.