As the holiest days in the Jewish and Muslim calendars, Yom Kippur and Ramadan, coincided, Egyptian and Syrian forces attacked Israel in an attempt to regain territory lost in the 1967 Six-Day War. The volatile conflict drew massive military resupplies to the opposing sides from the United States and Russia, and the two nuclear powers issued threats.  The resulting Arab oil embargo lasted, with crippling effects, until the following March, long after the hostilities ended with a United Nations ceasefire on October 25.