The captain of the Solong cargo ship who was arrested after crashing into an oil tanker off the English coast is a Russian national, the vessel’s owner said Wednesday, as maritime experts search for answers.

The police in Britain detained the ship’s captain on suspicion of gross negligence after it crashed into an oil tanker that was being operated by the U.S. Navy.

The captain of a cargo ship that collided with a U.S. tanker is a Russian national who remains in U.K. police custody, the vessel’s owner said Wednesday, as it emerged that the ship failed several safety checks last year.