<p>Scott Walker believes the idea of building a wall on the U.S.-Canada border is a "legitimate issue" — a statement that isn’t going over so well with Canada’s defense minister.</p><p>During his appearance on Meet the Press on Sunday, Walker was asked why he was so focused on securing the border with Mexico to thwart terrorists, when one of the highest profile incidents involved the northern border.</p><p>“Some people have asked us about that in New Hampshire.