WASHINGTON - Donald Trump says he won't stand for it if it turns out some of his hats labelled "Made in USA" actually weren't made in the USA.

The baseball-style "Make America Great Again" hats are indeed stitched together at a small factory in the Los Angeles area.

But in a small sample tested by The Associated Press and an outside expert, at least one did not contain the specific type of American-made fabric the manufacturer insists is always used for the hats.

The true origin of the fabric in that hat remains a mystery - whether U.S. or foreign made.  It shows how difficult it can be to verify something is actually made in the U.S.

Informed of AP's findings, Trump said any misrepresentation would be unacceptable.  He says: "I pay a good price for that hat. If it's not made in the USA, we'll bring a lawsuit."