The USS Tempest and USS Typhoon seized the drugs hidden aboard a stateless fishing vessel in the Middle East waters, the international task force said. The raid took place on Monday.
The Navy said the fishing vessel probably came from Iran. All nine crew members identified themselves as Iranian citizens, according to Cmdr Timothy Hawkins, a spokesman for the US Navy’s Fifth Fleet.
He did not elaborate on who manufactured the drugs or their ultimate destination.
As the task force steps up regional patrols, it has confiscated illegal drugs worth more than $193m during operations at sea this year – more than the amount of drugs seized in the past four years combined, the task force statement said.
Heroin is trafficked to the Middle East and even Europe by land from Iran and Afghanistan through well-worn land routes in the Balkans and Southern Caucasus Mountains, according to last year's UN Global Synthetic Drugs Assessment. Smugglers from Iran have increasingly taken to sea to bring heroin into South Asia, the report said, with Iranian and Pakistani seamen often arrested near Sri Lanka.
Iran's 1,923-kilometre eastern border with Afghanistan, the world’s largest producer of opium, has turned it into a key transit country for the illicit drug trade.