Japan, the European Union and Canada on Thursday expressed opposition to U.S. President Donald Trump's proposal of additional tariffs of up to 25 percent on imported cars and parts, insisting that such imports from the three allies pose no threat to U.S. national security.

"The importation of automobiles and auto parts from Japan has not by any means threatened to impair the national security of the United States, and will never do so in the future," Kazutoshi Aikawa, deputy chief of mission at the Japanese Embassy in Washington, said at a U.S. Commerce Department hearing.

European Union Ambassador David O'Sullivan criticized Trump's threat to impose auto import duties, saying, "The European Union reiterates its firm opposition to the proliferation of measures taken on supposed national security grounds for the purposes of economic protection."