OTTAWA, March 1 (Xinhua) — Canada said Thursday that the steep tariffs imposed by the United States on steel and aluminum were "unacceptable", vowing to take "responsive measures".

"As a key NORAD (North American Aerospace Defense Command) and NATO ally, and as the number one customer of American steel, Canada would view any trade restrictions on Canadian steel and aluminum as absolutely unacceptable," Canadian Foreign Minister Chrystia Freeland said in a statement.

U.S. President Donald Trump announced Thursday that he would impose tariffs on the importation of steel and aluminum products, in a move he claims would protect the U.S. industry.