Trump said in an address to the U.S. Congress that the pipeline would be one of the largest in the world.

"Japan, South Korea and other nations want to be our partner, with investments of trillions of dollars each," he said.

South Korea's industry ministry said Minister Ahn Duk-geun discussed the project with U.S. officials during a visit to Washington last week, but no details had been decided.

"We will actively engage in discussions with the United States moving forward as it is a matter of mutual interest of the two countries," a ministry spokesperson said after Trump's remarks.

Earlier on Tuesday, Ahn said the United States had asked South Korea and other countries if they were interested in participating in the Alaskan liquefied natural gas project.

He said Seoul and Washington had agreed to establish a working-level group to discuss the pipeline, energy, shipbuilding, tariffs and non-tariff barriers.

Ahn's visit to Washington was aimed at seeking exemptions from Trump administration tariffs that are expected to hit South Korea's export-reliant economy hard.

Japanese Prime Minister Shigeru Ishiba said on Wednesday expanding American gas, bioethanol and ammonia imports would "meet the national interests of both Japan and the U.S." as it would stabilize Japan's energy supply while reducing the U.S. trade deficit. He made similar remarks after meeting Trump last month.

"We will carefully examine its technical possibilities and profitability," Ishiba told a parliament session.

In the address to Congress, Trump highlighted his tariff plans and said it was now the turn of the United States to use tariffs against other countries as they had against the United States. He said he would impose reciprocal tariffs on April 2.

He said South Korea's average tariff was four times higher than that of the U.S., despite military and other assistance the United States has provided to the country.

South Korea's tariff rate on U.S. imports was around 0.79% as of last year under a free trade agreement between the two countries, Seoul's trade ministry said.

Seoul would actively communicate with Washington about its tariffs through multiple channels, the ministry added.

On Sunday, the co-chair of the White House National Energy Dominance Council Doug Burgum said the 800-mile LNG gas pipeline would allow the United States to sell energy to its allies and "raise money for the U.S. Treasury."

While the Alaska LNG proposal faces cost and logistical hurdles, Japan, South Korea, Taiwan and others are buying into the idea of increasing U.S. gas imports more broadly.

Japanese officials have not said they had agreed to participate in the pipeline but have agreed to look into the matter, according to people familiar with the conversations.

Japan's trade minister plans to visit Washington this month to seek exemptions from Trump's tariffs and discuss Japan's plans to buy more U.S. LNG.