After World War II and during the Cold War, Saudi Arabia maintained an anti-Communist, anti-secular Arab nationalist policy, often working with the leading anti-Communist power, the United States. Following the 1973 oil crisis, where Saudi Arabia and other Arab oil exporters embargoed the United States and its allies for their support of Israel, oil revenues increased dramatically and it worked to become the leading Islamic state, spending generously to advance Islam and particularly its conservative school (known as Wahhabism). The effect has been to purify and unify Islamic faith, according to supporters, and to erode regional Islamic cultures, according to others.