In November 1964, Faisal became the new king after the conflicts he had with his brother Saud, the erstwhile king. The U.S., on the other hand, was not sure about the outcome of such unplanned change in the Saudi monarchy. Faisal, however, continued the cooperation with the U.S. until October 20, 1973. Then came the low point of the relationship before 9/11, as Faisal decided to contribute in an oil embargo against the U.S. and Europe in favor of the Arab position during the Yom Kippur War. That caused an energy crisis in the U.S.