Yemeni authorities have seized a ship in the nation's territorial waters carrying explosives and weapons, including anti-aircraft missiles, reports say.
According to the state news agency the US said the ship came from Iran.
The report said Yemen's coast guard intercepted the ship last week in an operation co-ordinated with the US Navy. It did not say why news of the interception was not announced earlier.
The report said the vessel's eight crew members were Yemenis.
In Washington, Pentagon spokesman George Little told reporters that crew members said the ship came from Iran. He said the ship was seen operating "erratically" in Yemeni waters "and so a routine boarding (was) conducted", with US support. The cargo was inspected, and it included weapons, he said.
Yemen has recently witnessed several cases of illegal arms shipments through its porous shores on the Red and Arabian seas.
Yemen is home to an active branch of al Qaida, which staged several failed or foiled attacks on US territory over the past several years.
Officials said attacks by Yemen's air force killed at least 16 al Qaida militants and wounded dozens of others. The officials said the air force launched several air attacks in central Yemen, where the militants have bases.
In another operation, the Yemen military freed 13 soldiers captured by al Qaida.