FILE - In this file photo taken Wednesday, Dec. 5, 2007, a Chinese worker performs welding work on steel rods using a steel drill at a construction site in Beijing. China says it "firmly opposes" U.S. President Donald Trump's tariff increase for imported steel and aluminum but gave no indication whether Beijing might impose its own measures in response. A government statement issued Friday, March 9, 2018, accused Trump of damaging the global trading system. (AP Photo/Ng Han Guan, File)

BEIJING - China accused U.S. President Donald Trump on Friday of damaging the global trading system by hiking steel and aluminum tariffs, while Japan and South Korea expressed alarm at potential economic damage.

China's Commerce Ministry said it "firmly opposes" Trump's move but gave no indication whether Beijing might make good on threats to retaliate.

Asian stock markets rose in early trading on relief that Trump's measures were not more severe. Traders also were encouraged by news Trump might meet North Korean leader Kim Jong-un.

South Korea's trade minister, speaking at an emergency meeting, appealed to other governments to prevent a "trade war."

"We will urge the international community to refrain from adopting measures that inhibit free trade," said the minister, Paik Un-gyu, according to a ministry statement.

Trump said the tariff hikes ordered Thursday were needed to protect U.S. national security by ensuring the survival of the country's metals producers.

"These measures could make a significant impact on the economic and co-operative relationship between Japan and the U.S., who are allies," said Taro Kono, Japan's trade minister, in a statement.

The new tariffs take effect in 15 days, with Canada and Mexico indefinitely spared "to see if we can make the deal," Trump said, referring to a possible renegotiation of the North American Free Trade Agreement. He suggested at a Cabinet meeting that Australia and "other countries" might be spared, a shift that could soften the blow amid threats of retaliation.

Trump has complained about low-cost Chinese exports of steel and aluminum, but the latest move was likely to hit Japan and South Korea harder.

The United States bought just 1.1 per cent of China's steel exports last year compared with 12 per cent for South Korea and 5 per cent for Japan, according to the U.S. International Trade Commission.

"Significant damage in South Korea's steel exports to the United States seems unavoidable," said Paik's statement.

Australia's trade minister said he had preliminary discussions with the U.S. trade representative, Robert Lighthizer. The minister, Steve Ciobo, expressed hope of "finalizing a positive outcome in the next two weeks."

The Chinese Commerce Ministry criticized Trump for taking unilateral action instead of working through the World Trade Organization.

"The misuse of the 'national security exception' clause by the United States is wanton destruction of the multilateral trade system represented by the WTO and will surely have a serious impact on the normal international trade order. China firmly opposes it," said a Commerce Ministry official, Wang Hejun, in a statement.

Beijing said it was ready to retaliate in the event Chinese companies are hurt, but Friday's statement gave no indication of official action.

"The U.S. pursues trade protectionism," said the China Iron & Steel Association, an industry group, in a statement.

"This move will harm the global steel industry, and seriously hurt consumers' interests," said the statement. It said the United States "will injure others and harm itself."

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AP writers Mari Yamaguchi and Yuri Kageyama in Tokyo and Youkyung Lee in Seoul contributed.

News from © The Associated Press, 2018