(1980–90) Protracted and indecisive conflict prompted by Iraq's invasion of its eastern neighbour.
Following the 1979 Iranian revolution, the Iraqi leadership sought to exploit Iran's military and political chaos in order to resolve border disputes, gain control of Iran's oil-rich western (largely Arab) province, and achieve hegemony in the Persian Gulf. Iraq was successful early (1980–82) but began to lose ground and sought to negotiate peace. Iran refused, and the war turned into a bloody stalemate that included the first use of chemical warfare since World War I (1914–18). After additional Iraqi advances, Iran agreed to a cease-fire in 1988. Peace was concluded only when Iraq invaded another neighbour, Kuwait, in 1990. See also Saddām Hussein ; Ruhollah Khomeini .