Five months later, South Korea submitted an appeal with the WTO against the tariff, arguing that the US calculation of margins for Korean products was not "reasonable" when compared with the rate of global profit margins.

In November of last year, the WTO dispute settlement panel sided with Seoul's claim that the US incorrectly applied the term "same general category of products" in determining for OCTG products and didn't use the actual profit data. The Korean companies exported 98 percent of their products to the United States.

The ruling was confirmed as the US did not appeal within 60 days.

South Korea exported $818 million worth of OCTG to the world's largest economy in 2013, but the amount shrank to $262 million in 2015 and $271 million in 2016, the ministry said.

Meanwhile, Trade Minister Paik Un-gyu said the government will firmly deal with growing protectionist moves against steel imports.

"The government will firmly cope with unreasonable import regulations," Paik said during a meeting with senior officials from local steelmakers. "I hope local steelmakers will also make efforts to diversify their export destination and take measures against possible import regulations raised by other countries."

The Donald Trump administration has invoked Section 232 of the Trade Expansion Act, a rarely used tool that allows emergency trade sanctions on "national security" grounds in an apparent precursor to fresh trade barriers to foreign steel imports.

In April last year, Trump ordered a probe into whether steel imports undermined US national security.

South Korean officials have reiterated that they will actively tackle any unfair trade barriers that can be imposed on South Korean products by foreign countries, including by filing complaints with the WTO. (Yonhap)