Following a long dispute between borders and stemmed from fear of the Iranian revolution Iraq instigated the war out of desire to become the dominant Persian Gulf state. Another large factor pushing in the war was the long held conflict between the Sunni and Shia split between Muslims (Iran, primarily Shia, and Iraq, primarily Sunni). These countries fought over the balance of power in these religious sects.
The US needed to decide which side they would support in this war. Considering the recent beef the U.S had with Iran for holding 53 Americans hostage (who were released on the day of Reagan's inauguration), the U.S chose to only support Iraq. The US gave Iraq diplomatic, monetary, intelligence and military support. In the end, the war ended as a stalemate--but today both countries are primarily Shia.
The US needed to decide which side they would support in this war. Considering the recent beef the U.S had with Iran for holding 53 Americans hostage (who were released on the day of Reagan's inauguration), the U.S chose to only support Iraq. The US gave Iraq diplomatic, monetary, intelligence and military support. In the end, the war ended as a stalemate--but today both countries are primarily Shia.