Enough fentanyl has been seized in the US to kill every American, federal drug agents have revealed.
More than 397 million fatal fentanyl doses have been intercepted, according to the Drug Enforcement Administration (DEA) - with just two milligrams enough to be deadly.
The drug is a highly addictive substance and 50 times more lethal than heroin, with the opioid being mostly trafficked into the US from Mexico.