U.S. Sen. Amy Klobuchar on Tuesday doubled-down on last week’s ruling by the Commerce Department that South Korea and eight other countries are illegally dumping steel pipe into the U.S. market.

The senior Democratic Minnesota senator addressed the International Trade Commission, urging members to sanction the department’s ruling of unfair competition and impose significant penalties on South Korean firms to offset any gains they have achieved through their illegal dumping.

Of the nine countries, South Korea is the dominant culprit of dumping Oil Country Tubular Goods into the U.S. That pipe is used in the flourishing American oil and gas fracking business, which is driving the United States toward energy self-sufficiency.

However, South Korea doesn’t even have a domestic market for OCTG.

Klobuchar told the ITC that all American ore and steel companies and their workers are seeking is a fair playing field.

“Through the generations, our miners on the Range have proven they can compete with anybody in the world when it comes to providing quality steel.

“I don’t think my grandpa, when he worked those 1,500 feet underground in the iron ore mines, ever thought of dumping practices or South Korean OCTG products coming in. He didn’t think about that. He just wanted to do a fair day’s work for a fair day’s pay. The miners of today deserve the same treatment,” Klobuchar said.

The senator urged commission members to put penalties in place.

“Now that the investigation has found clear evidence of Korean companies dumping steel into the U.S., the ITC needs to impose penalties on these firms and continue cracking down on illegal trade practices that hurt local economies in Minnesota and across the country,” she said.