South Korea went to the WTO in 2014 to challenge US tariffs levied on oil country tubular goods (OCTG), a type of steel piping used in the energy industry.
Washington said its tariffs aimed to stop South Korea exporting the product at unfairly cheap prices. After South Korea won a partial victory at the WTO, the US had until July 12 to comply with that ruling.
South Korea said the US had failed to do so and it was seeking sanctions equal to the level of trade harm done.
“Based on available data, this level is estimated at $350m annually. This amount will be adjusted by applying the annual growth rate of the OCTG market of the US,” it said in the sanctions request published by the WTO.