On 20 July, the UN Security Council passed the U.S.-sponsored Resolution 598, which called for an end to the fighting and a return to pre-war boundaries. This resolution was noted by Iran for being the first resolution to call for a return to the pre-war borders, and setting up a commission to determine the aggressor and compensation.
His first major break came from his starring role in director Barry Levinson's Good Morning, Vietnam (1987), which earned Williams a nomination for the Academy Award for Best Actor. The film is set in 1965 during the Vietnam War, with Williams playing the role of Adrian Cronauer, a radio shock jock who keeps the troops entertained with comedy and sarcasm. Williams was allowed to play the role without a script, improvising most of his lines. Over the microphone, he created voice impressions of people, including Walter Cronkite, Gomer Pyle, Elvis Presley, Mr. Ed, and Richard Nixon. "We just let the cameras roll," said producer Mark Johnson, and Williams "managed to create something new for every single take."