Japan's top government spokesman said on Friday that Japan would continue to ask the United States to exempt it from Washington's plan to impose tariffs on imports of steel and aluminum.

Chief Cabinet Secretary Yoshihide Suga told a news conference that Japan's steel and aluminum shipments did not pose a threat to U.S. national security and that they contributed greatly to employment and industry in the United States.

Also on Friday, Foreign Minister Taro Kono said in a statement that the United States' decision to impose tariffs on steel and aluminum was "regrettable" and will likely have a "big impact" on economic ties between Japan and the United States.

Kono said the decision would also impact the global economy, adding that Japan would respond appropriately upon examining any impact on Japanese companies and World Trade Organization rules.

U.S. President Donald Trump pressed ahead on Thursday with import tariffs of 25 percent on steel and 10 percent for aluminum but exempted Canada and Mexico and offered the possibility of excluding other allies, backtracking from an earlier "no-exceptions" stance.