This refers to the crisis in Iranian-U.S. relations. In October 1979, the U.S. Government agreed to allow the former Shah, Reza Pahlavi, to go to the United States. The following month, Iranian students took the staff of the U.S. Embassy in Iran hostage to press their demand that the United States send the ex-Shah back to Iran to face trial and return all Iranian assets in the United States. Hence the Iranian-U.S. crisis.