WHISTLER, Canada — Japanese Finance Minister Taro Aso said Friday the U.S. tariffs on steel and aluminum are “extremely regrettable,” and that Tokyo could file a challenge with the World Trade Organization.

“It is undecided at this moment, but we are considering it,” Aso told reporters when asked about the possibility of a WTO action against the U.S. levies which Washington claims are necessary for national security.

Canada launched a WTO challenge to the U.S. tariffs Friday and the European Union said it will also do so after Washington imposed the steel and aluminum levies on their exports “to protect America’s national security from the effects of global oversupply.”

The 25 percent tariff on steel imports and 10 percent tariff on aluminum imports from Canada, the European Union and Mexico took effect Friday.

The issue was a key topic of discussion at the meeting of Group of Seven finance ministers and central bankers in the Canadian ski resort of Whistler.

The three-day meeting has brought together finance officials from Britain, Canada, France, Germany, Italy, Japan, the United States and the European Union.

The six other members and the European Union all voiced opposition to the U.S. tariffs, Aso said after the second day of the talks.

“The unilateral protectionist move does not benefit any country,” Aso said.

French Finance Minister Bruno Le Maire said the United States was isolated during the discussion on trade. He was quoted by Reuters news agency as saying the group devolved to “G-6 plus one.”

European Commission President Jean-Claude Juncker has said the tariffs are targeted at countries not responsible for overcapacities, calling the U.S. duties “protectionism, pure and simple.”

In a meeting Thursday with U.S. Treasury Secretary Steven Mnuchin, Aso pushed for Japan’s permanent exemption from the U.S. tariffs and asked for restraint when considering new automobile duties. The U.S. Commerce Department recently launched an investigation into imported cars, trucks and auto parts.