The U.S. Navy’s Fifth Fleet said on Sunday it had seized a huge cache of illicit Russian and Chinese weapons from a stateless dhow sailing in the international waters of the Arabian Sea.

The Bahrain-based Fifth Fleet said the guided-missile cruiser USS Monterey intercepted the ship and discovered the cargo during a routine embarkation, during a two-day operation on May 6 and 7.

“The weapons cache 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,” he said in a press release.

The weapons are in the hands of the United States and their source and destination are under investigation, he said.

The Fifth Fleet said the Monterey was in service for 36 hours, ensuring the safety of boarding teams.

“Once all the illegal cargoes were removed, the dhow was assessed for seaworthiness, and after questioning, its crew were given food and water before being released.”

The statement did not indicate where the ship might have come from, but indicated that regular US Navy patrols in the region “disrupt the transport of illicit goods which often finance terrorism and illegal activities.”