The story behind it:

The 1973 oil crisis began in earnest on October 17, 1973, when the members of Organization of Arab Petroleum Exporting Countries (OAPEC, consisting of the Arab members of OPEC plus Egypt and Syria) announced, as a result of the ongoing Yom Kippur War, that they would no longer ship petroleum to nations that had supported Israel in its conflict with Syria and Egypt (i.e., to the United States and its allies in Western Europe).

The Yom Kippur War

The persistence of the Arab-Israeli conflict finally triggered a response that transformed OPEC from a mere cartel into a formidable political force. After the Six Day War of 1967 the Arab members of OPEC formed a separate, overlapping group (Organization of Arab Petroleum Exporting Countries) for the purpose of centering policy and exerting pressure on the West over its support of Israel. Egypt and Syria, though not major oil-exporting countries, joined the latter grouping to help articulate its objectives. Later, the Yom Kippur War of 1973 galvanized Arab opinion. Furious at the emergency re-supply effort that had enabled Israel to withstand Egyptian and Syrian forces, the Arab world imposed the 1973 oil embargo against the United States, Western Europe, and Japan. By the early 1970s the great Western oil conglomerates suddenly faced a unified bloc of producers.