International aid to combatants in the Iran–Iraq War

During the Iran–Iraq War, both Iran and Iraq received large quantities of weapons and other material useful to the development of armaments and weapons of mass destruction.

Military support
Iran was backed by the Kurdish militias of KDP and PUK in North Iraq, both organizations in fact rebelling against Iraqi Ba'athist government with Iranian support.

Logistic support
Iran's foreign supporters gradually came to include Syria and Libya, through which it obtained Scud missiles. It purchased weaponry from North Korea and the People's Republic of China, notably the Silkworm anti-ship missile. It also acquired arms from Portugal, notably after 1984.

Military support
Iraq was supported by an Iranian outcast-armed party of Mujaheddin el-Halq, mainly engaging the pro-Iranian Kurdish forces in the North of Iraq, close to Iranian borders.

Logistic support
Iraq's army was primarily equipped with weaponry it had previously purchased from the Soviet Union and its satellites in the preceding decade. During the war, it also purchased billions of dollars' worth of advanced equipment from France, the People's Republic of China, Egypt, Germany and other sources. Iraq's three main suppliers of weaponry during the war were the Soviet Union followed by China and then France. It also acquired substantial arms from Portugal.

The United States sold Iraq over $200 million in helicopters, which were used by the Iraqi military in the war. These were the only direct U.S.-Iraqi military sales. At the same time, the CIA began covertly directing non-U.S. origin hardware to Saddam Hussein's armed forces, "to ensure that Iraq had sufficient military weapons, ammunition and vehicles to avoid losing the Iran-Iraq war."

Germany, the U.S. and United Kingdom also provided "dual use" technology that allowed Iraq to expand its missile program and radar defenses.

According to an uncensored copy of Iraq's 11,000-page declaration to the U.N., leaked to Die Tageszeitung and reported by The Independent, the know-how and material for developing unconventional weapons were obtained from 150 foreign companies, from countries such as West Germany, the U.S., France, UK, and the People's Republic of China.

Iraq's main financial backers were the oil-rich Persian Gulf states, most notably Saudi Arabia ($30.9 billion), Kuwait ($8.2 billion) and the United Arab Emirates ($8 billion).

The Iraqgate scandal revealed that an Atlanta branch of Italy's largest bank, Banca Nazionale del Lavoro, relying largely on U.S. taxpayer-guaranteed loans, funneled $5 billion to Iraq from 1985 to 1989.

United States
During the early years of the war, Iran's arsenal was almost entirely American-made, left over from the Imperial Armed Forces of the dethroned Shah.

Iran-Contra affair
Iran acquired weapons and parts for its Shah-era U.S. systems through covert arms transactions from officials in the Reagan Administration, first indirectly through Israel and then directly. It was hoped Iran would, in exchange, persuade several radical groups to release Western hostages, though this did not result; proceeds from the sales were diverted to the Nicaraguan Contras in what became known as the Iran-Contra Affair.

Intelligence
Prior to the 1979 revolution, the U.S. had been providing intelligence to Iran. In mid-October 1979, at the request of the United States Department of State, a CIA officer went to Tehran and warned the government, mid-October 1979, of Iraq's plan to invade. U.S. cooperation of this type stopped when the U.S. embassy was seized.

Strategic intent
Author George Crile, in his book Charlie Wilson's War, writes regarding CIA involvement in the Iran–Iraq War: "As explained by Ed Juchniewicz - Avrakotos's patron and the number two man in the Operations Division at that time - they were just leveling the playing field: 'We didn't want either side to have the advantage. We just wanted them to kick the shit out of each other'."

In 1985, a CIA analyst, Graham Fuller, had proposed that the U.S. should offer to sell weapons to Iran, as a means of blocking Soviet influence there. Robert M. Gates, then head of the CIA National Intelligence Council, advanced the suggestion, which circulated over the signature of Director of Central Intelligence William Casey. The section was rejected by the incumbent Secretary of State George Schultz and Secretary of Defense Caspar Weinberger.