As Brzezinski took control of the negotiations, Vance was marginalized and his influence began to wane. When revolution erupted in Iran in late 1978, the two were divided on how to support the United States' ally the Shah of Iran. Vance argued in favor of reforms while Brzezinski urged him to crack down – the 'iron fist' approach. Unable to receive a direct course of action from Carter, the mixed messages that the Shah received from Vance and Brzezinski contributed to his confusion and indecision as he fled Iran in January 1979 and his regime collapsed.