Why us helped Iraq in war against Iran?

The U.S. supported Iraq during the Iran-Iraq War (1980-1988) primarily to counter the spread of Iranian influence following the 1979 Iranian Revolution. By backing Iraq, the U.S. aimed to maintain a balance of power in the region and prevent the establishment of a Shiite Islamic regime that could threaten U.S. interests and allies in the Middle East. This support included intelligence sharing, economic aid, and military supplies, reflecting a strategic choice to contain Iran rather than support Iraq's authoritarian regime.