President Donald Trump displays a signed proclamation regarding steel imports as he speaks in the Oval Office at the White House, Feb. 10, in Washington, D.C., as Commerce Secretary nominee Howard Lutnick watches. AP-Yonhap

U.S. President Donald Trump announced plans Monday to impose 25 percent tariffs on all steel and aluminum imports coming into the United States "without exceptions or exemptions," raising concerns over its ramifications on Korean and other exporters.

Trump signed two proclamations regarding the sweeping tariffs, while affirming a plan to announce "reciprocal" tariffs "over the next two days" — duties on U.S. imports designed to match tariff rates that other countries impose on U.S. exports.

During his first term, Trump imposed a 25 percent tariff on steel imports and 10 percent on aluminum imports on national security grounds. The new measures will remove exceptions, exemptions and duty-free quotas for U.S. trading partners, while raising the tariff on aluminum to 25 percent. They are set to take effect on March 4, according to Reuters.

"Today, I am simplifying our tariffs on steel and aluminum so that everyone can understand exactly what it means. It's 25 percent without exceptions or exemptions, and that's all countries, no matter where it comes from," Trump told reporters as he signed the documents.

"If it's made in the United States, there is no tariff. All you have to do is make it in the United States. We don't need it from another country," he added.

Announcing what he cast as "massive" tariffs," Trump claimed that America was "being pummeled by both friend and foe alike."

"Our nation requires steel and aluminum to be made in America, not in foreign lands. We need to create in order to protect our country's future resurgence of U.S. manufacturing and production, the likes of which has not been seen for many decades," he said.

"It's time for our great industries to come back to America ... This is the first of many."

Asked about what the president plans to do if other countries retaliate, Trump said, "I don't mind.

"If they retaliate, as I said, it's reciprocal," he said. "If they raise it a little bit, then we raise it automatically. So I don't think it helps for them to retaliate."

U.S. President Donald Trump speaks to the press after signing an executive order in the Oval Office of the White House in Washington, D.C., Feb. 10. AFP-Yonhap

Trump also warned that his administration is looking into the possible imposition of tariffs on cars, semiconductors and pharmaceuticals, among other items.

"Cars is going to be a very big one and a very important one, and America is going to be stronger than it ever was before," he said.

Ahead of the announcement, Korea's acting President and Deputy Prime Minister Choi Sang-mok presided over a meeting of top government officials Monday (Seoul time) to discuss the potential ramifications of new U.S. tariffs on metals and the country's responses.

Last year, Korea exported 28.35 million tons of steel products, with 2.77 million tons shipped to the United States, according to the Korea Iron & Steel Association. Canada, Mexico, Brazil and Korea are among the top exporters of steel into the U.S.

Trump has already imposed a 10 percent tariff on all Chinese goods coming into the U.S., while he has paused the imposition of a 25 percent tariff on Canada and Mexico temporarily as the two countries agreed to step up efforts to prevent drug trafficking at their borders with the U.S. (Yonhap)