The early 1980s recession was a severe economic recession that affected much of the world between approximately the start of 1980 and early 1983. It is widely considered to have been the most severe recession since World War II. A key event leading to the recession was the 1979 energy crisis, mostly caused by the Iranian Revolution which caused a disruption to the global oil supply, which saw oil prices rising sharply in 1979 and early 1980. The sharp rise in oil prices pushed the already high rates of inflation in several major advanced countries to new double-digit highs, with countries such as the United States, Canada, West Germany, Italy, the United Kingdom and Japan tightening their monetary policies by increasing interest rates in order control the inflation. These G7 countries each, in fact, had "double-dip" recessions involving short declines in economic output in parts of 1980 followed by a short period of expansion, in turn followed by a steeper, longer period of economic contraction starting sometime in 1981 and ending in the last half of 1982 or in early 1983. Most of these countries experienced stagflation, a situation of both high interest rates and high unemployment rates.