What is a threat? Who is the threat? Who is the greatest threat to the world?

Who is a threat, what is a threat? This concept of threat is a trade mark of American hegemony. The Americans have been declaring this country and that country as a threat to them. Can anyone visualise how little countries or poor farmers in Afghanistan or some poor country be a threat to the biggest and most powerful Empire in history? Can North Korea or Iran really be a threat to the Americans