Iran
Despite its poor relationship with the U.S. and Great Britain, the Iranian military used primarily U.S. and British equipment which it inherited from the days of the Shan. This included a state of the art U.S. supplied air force which was in many ways only outdone by that of the U.S. and the U.S.S.R.. This proved to be a great boon at the beginning of the war as Iran was able to contest the Iraqi air force which was assumed by Saddam to be dominate throughout the war. It did however present problems later in the conflict as spare parts for the air force was extremely difficult to come by meaning that Iran became more and more reliant on weapons bought from the Soviet Union, China and North Korea.
Using North Korea as an intermediate Iran was able to purchase large quantities of weapons from both the Soviet Union and China. Purchases included large amounts of tanks and plans for a huge purchase of Chinese F-7 jets which never materialized. From the U.S., 2,000 TOW missiles and spare parts for the HAWK missile system were sent to Iran as part of the clandestine Iran-Contra Affair. As a whole however Iranian imports of weapons pales in comparison to the Iraqi purchases due to the efforts of the U.S. to reduce the amount of weapons going to Iran through Operation Staunch in 1983 which targeted Spain, Portugal, South Korea, and Italy. Israel took direct military action in the Iran-Iraq war by striking the Iraqi nuclear reactor on 7 June 1981 in Operation Opera.
Iraq
Despite occurring during the Cold War, the Iran-Iraq War cannot be viewed in the same context as other wars such as Korea, Vietnam, the Soviet Invasion of Afghanistan, and many others of the era. Iraq was, along with many other Arab states, closely associated with the Soviet Union. Up until the 1970s Iraq received almost all of its weapons from the Soviet Union but under Saddam Hussein, Iraq looked increasingly to Western Europe, particularly France, to diversify its weapon imports. The Iraqi air force was largely composed of Soviet aircraft including the Tu-22, Su-17 and Mig-23, but during the war Iraq was able to receive advanced jets from France such as the F-1 Mirage. Much of the equipment from early on in the war was bought directly from the Soviet Union including many tanks, helicopters, artillery, anti-aircraft missiles and so on.
As the war dragged on, more and more countries saw the potential to both expand their influence in the region as well as make money selling weapons. Iraq was able to receive a considerable amount of weapons and funding from other Arab neighbors including Egypt, Jordan, Kuwait, Qatar, Saudi Arabia, and the United Arab Emirates. Support from Europe came in the form of high-tech weapon systems primarily from France, Italy, Western Germany, Spain, and the United Kingdom. Towards the conclusion of the war the United States government allowed the purchase of dual-use technology such the sale of Bell helicopters designed for spraying pesticides which were converted to be used in chemical weapon attacks. U.S. support was increased drastically after it appeared that Iran was gaining the upper-hand in the conflict. Relations between the U.S. and Iraq were previously cut off due to Iraqi support of the Arab states in the Arab-Israeli Conflicts, but were restored between 1982 and 1983. The U.S. also greatly assisted in an undeclared stalemate in the Persian Gulf to the benefit of Iraq and attacked several Iranian mine ships and attacked Iranian platforms in Operation Praying Mantis.