U.S. President Donald Trump promised to crack down on dumping of cheap steel by foreign competitors, adding that he’s considering imposing new tariffs or quotas on imports.

“Steel is a big problem. Steel is—I mean, they’re dumping steel. Not only China, but others,” Trump told reporters Wednesday evening on Air Force One on a trip to France. “We’re like a dumping ground, OK? They’re dumping steel and destroying our steel industry, they’ve been doing it for decades, and I’m stopping it. It’ll stop.”

The president said there are two ways the U.S. can stop dumping, by imposing tariffs or quotas on steel imports. “Maybe I’ll do both,” he said.

U.S. steelmaking stocks headed for their best week in four months following the publication of Trump’s comments on Thursday. AK Steel Holding Corp. jumped as much as 9 percent, U.S. Steel Corp. advanced 5.5 percent and Nucor Corp. climbed as much as 3.3 percent. The Bloomberg Americas Iron/Steel Index extended a weekly gain to 4.5 percent, the most since mid-March.

Countries from Canada to China have been bracing for the result of a Commerce Department investigation into whether steel imports threaten U.S. national security. Officials within the administration have been debating several options, including raising tariffs on steel imports, according to people briefed on the discussions.

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Trump ordered Commerce earlier this year to probe steel imports under the seldom-used Section 232 of the Trade Expansion Act of 1962, which allows the president to impose trade measures if the government finds evidence of a national-security threat from foreign shipments.

Commerce Secretary Wilbur Ross briefed members of the Senate Finance Committee on the steel investigation on Thursday in Washington. While Commerce has until early next year to hand over the report, Secretary Ross has said he wants to complete it soon, though he already missed a self-imposed deadline at the end of June. Ross on Thursday declined to tell reporters the new target date for finishing the study, after briefing members of the Senate Finance Committee in Washington.

Ross told the lawmakers during the meeting he will present options to the president, who will make the ultimate decision on steel imports, according to Republican Senator Pat Roberts, who attended the briefing.

Former Federal Reserve chairmen Ben Bernanke and Alan Greenspan and other leading economists are warning Trump that new tariffs on steel would raise costs for U.S. manufacturers, increase prices for consumers and harm relations with allies.

While Trump and members of his cabinet have accused China of dumping cheap steel on global markets, tariffs may not do much to reduce excess supply, since the U.S. imports a relatively small amount of its steel from Chinese producers. Canada is the biggest foreigner supplier of steel to the U.S.