WASHINGTON—The Trump administration announced on March 11 the launch of new trade investigations to address unfair trade practices as it seeks to replace reciprocal tariffs recently struck down by the Supreme Court.

There will be two separate investigations under Section 301 of the Trade Act of 1974, which may result in tariff increases on certain countries, U.S. Trade Representative Jamieson Greer said in a call with reporters.

The first investigation, initiated on March 11, will focus on addressing trade practices related to excess capacity and production in manufacturing sectors.

According to Greer, the trading partners subject to this investigation are China, the European Union, Singapore, Norway, Indonesia, Malaysia, Cambodia, Thailand, South Korea, Vietnam, Taiwan, Bangladesh, Mexico, Japan, and India.

The second investigation, set to launch on March 12, will focus on imports produced with forced labor and target roughly 60 countries, he said. The investigation could result in a ban on imports of such goods.

The investigations will focus on economies that “appear to exhibit structural excess capacity and production in various manufacturing sectors, such as through larger, persistent trade surpluses or underutilized or unused capacity,” Greer said.

The probes come after the Supreme Court recently invalidated tariffs imposed by U.S. President Donald Trump on trading partners using the International Emergency Economic Powers Act.

Greer said the United States will be consulting with its trading partners that are subject to the new investigations into excess capacity.

“Our view is that key trading partners have developed production capacity that is really untethered from the market incentives of domestic and global demand,” he said.

Greer noted that the issue leads to persistent and large trade surpluses for those trading partners.

The investigation will examine several factors, including government subsidies, wage practices, non-commercial activities by state-owned or controlled enterprises, barriers to foreign exports, weak environmental or labor protections, subsidized lending, currency practices, and other relevant issues.

“Responsive action” could take several forms, according to Greer.

He noted that during the Section 301 investigation of China in Trump’s first term, the response included not only tariffs but also restrictions on foreign investment by the Treasury Department, tighter export controls by the Commerce Department, and a World Trade Organization case on intellectual property.

Following the Supreme Court ruling, Trump announced on Feb. 20 that he would issue an executive order, establishing a 10 percent “global tariff” under Section 122 of the Trade Act of 1974. Soon after, he signed an executive order to impose 10 percent global tariffs. He also said he would raise the rate to 15 percent, but he has not yet taken official action to do so.

Section 122 allows the president to implement a tariff rate of up to 15 percent on countries that maintain “large and serious” trade surpluses with the United States. The measure also authorizes the president to introduce limits on the volume of foreign goods entering the country.

The tariff may be imposed for up to 150 days. Extending it would require congressional approval, which may be difficult as the midterm elections approach.

Greer said that the administration is focused on completing the Section 301 investigations “as quickly as possible,” aiming to reach a conclusion before the Section 122 deadline.

He also said the administration plans to initiate additional trade investigations.

“We do expect that there will be other Section 301 investigations on a country-specific basis, or maybe other tools,” Greer said.

The U.S. trade representative earlier indicated that there would be new trade investigations covering discrimination against U.S. technology companies, digital goods and services, and digital services taxes. He also stated that his office will investigate trading partners’ practices concerning seafood, rice, and other products.

Andrew Moran and Aldgra Fredly contributed to this report.