The 1970s energy crisis was a period when the major industrial countries of the world, particularly the United States, Canada, Western Europe, Japan, Australia, and New Zealand, faced substantial petroleum shortages, real and perceived, as well as elevated prices. The two worst crises of this period were the 1973 oil crisis and the 1979 energy crisis, when the Yom Kippur War and the Iranian Revolution triggered interruptions in Middle Eastern oil exports.