Though this document deals specifically with LT/P tires, the following statement is true REGARDLESS of tire type:
Here quoting from page 8, paragraph 1:
.31 Domestic and imported tires sold in the U.S. market must meet the same National Highway Traffic Safety Administration standards and be marked in accordance with U.S. Department of Transportation requirements.32
There's no reason to believe there's some kind of International Conspiracy exempting ST tires from those standards.
Well, unless one considers belief in internet forum myths to be a reason...:R