On November 4, 1979, 52 American diplomats and citizens were held hostage by an Iranian student group in Tehran's U.S. Embassy. After the resignation of Cyrus Vance left a gap in the negotiations for the hostages, Muskie appealed to the United Nations (U.N.) and the government of Iran to release the hostages to little success. Already six months into the hostage crisis, he was pressed to reach a diplomatic solution. Before he assumed the position, the Delta Force rescue attempt called Operation Eagle Claw resulted in the death of multiple soldiers, leaving military intervention a sensitive course of action for the American public. He established diplomatic ties with the Iranian government and attempted to have the hostages released yet was initially unsuccessful. On January 15, as Muskie was flying to address the Maine Senate in Augusta, President Carter called him as his jet was touching down at Andrews Air Force Base. Carter alerted him that there was a possible breakthrough in the negotiations conducted by his deputy secretary Warren Christopher. After the negotiations failed, Muskie instructed the state department to continue seeking an agreement for the hostages' release. On January 20—the inauguration day of Ronald Reagan—the fifty-two hostages were handed over to U.S. authorities, a solution that had eluded Muskie and the entire Carter administration for 444 days and contributed to Carter's defeat.