The cruiser USS Monterey stopped the stateless dhow on May 6 during a routine operation to verify its registry, the Navy said.
A US Coast Guard Advanced Interdiction Team deployed on the Navy ship then boarded the dhow and found the weapons stash.
The massive arms haul covered much of the rear flight deck of the 567-foot (173-meter) US warship after it was transferred over in what the Navy said was a two-day operation.
“The cache of weapons included dozens of advanced Russian-made anti-tank guided missiles, thousands of Chinese Type 56 assault rifles, and hundreds of PKM machine guns, sniper rifles and rocket-propelled grenade launchers. Other weapon components included advanced optical sights,” the Navy statement said.
The US military was investigating the source and the intended destination of the huge weapons cache, which will remain in US custody, the Navy said.
After the dhow was deemed seaworthy and its crew was questioned, they were provided with food and water and released, according to the statement.