Donald Trump has signed an executive order making it a crime to excessively stockpile personal protective equipment that is needed by medical personnel fighting the coronavirus pandemic.
Attorney general William Barr said the Justice Department has already launched investigations into people who are hoarding supplies and price gouging.
He said investigators will go after people who are “hoarding these goods on an industrial scale for the purpose of manipulating the market”.
The executive order allows the president to designate some items as “scarce”.
Mr Barr said: “If you are sitting on a warehouse with surgical masks, you will be hearing a knock on your door.”
No specific items have been identified yet and the Justice Department will work with Health and Human Services to enforce the president’s order.