Japan's involvement, in the final analysis, is out of its own needs. Due to a long distance and a high transportation cost, Japan has to pay US$ 1 higher per barrel than European countries and the U.S. when importing oil from the Persian Bay. The recent ups and downs in the Persia also prompted Japan to diversify channels for importing oil, thereby casting off the over-reliance on the Persia for oil supply. In addition, the Japanese government has lately announced that it did not rule out the possibility of importing oil from other countries in special occasions in order to make it an important method for getting out from the domestic economic slump. Now Japan's strategic oil reserve has reached 0.6bn barrels, equivalent to the total oil demand for 172 days.