The tanker war, part of the larger Iran–Iraq War, was a series of military attacks by Iran and Iraq against merchant vessels in the Persian Gulf and Strait of Hormuz from 1981 to 1988. Iraq was responsible for 283 attacks. Iran accounted for 168.^[1]

The Iran–Iraq war began in September 1980.^[1] Before 1984, attacks against shipping had occurred, albeit on a much smaller scale.^[3] In December 1980, UN Secretary General Kurt Waldheim appealed to Iran and Iraq to ensure the security of peaceful shipping in the Persian Gulf.^[3] At that time, Iran assured other countries that it would keep the Strait of Hormuz open.^[3]

In his 1988 review paper, naval affairs analyst Ronald O'Rourke wrote that "Iran trapped or destroyed many Iraqi ships in port in the early stages of the war. But Iraq started the tanker war in the Gulf proper in 1981 by initiating attacks on ships steaming to or from Iranian ports at the extreme northern end of the Gulf. Iraq continued these attacks into 1984 without a parallel Iranian response at sea. In March of that year, Iraq increased the rate of its attacks and expanded their geographic scope by attacking ships serving more southerly Iranian points, particularly the oil-loading complex at Kharg Island. Two months later, Iran initiated its own attacks, and the tanker war became a two-way affair."^[1]

In 1984, Iraq broadened the tanker war by attacking the oil terminal and oil tankers at Kharg Island.^[4][5] Iraq's aim in attacking Iranian shipping was to provoke the Iranians to retaliate with extreme measures, such as closing the Strait of Hormuz to all maritime traffic, thereby bringing about foreign intervention against Iran; the United States had threatened several times to intervene if the Strait of Hormuz were closed.^[5] Kuwait and Saudi Arabia supported Iraq against Iran. The United States intervened in the conflict in 1986 to protect Kuwaiti tankers, and engaged in a confrontation with Iran.^[6]

Both sides had declared an "exclusion zone", meaning areas in which they had warned ships from entering. Iraq declared the area around Iran's Kharg Island to be an exclusion zone.^[7] Kharg Island hosted Iran's principal oil shipment port.^[8] Iraq gave precise definition, in coordinates, of this exclusion zone and gave advance notification to all countries.^[9] However, Iraq did not designate any safe passage routes in this zone.^[9]

Iran declared all waters within 40 miles of its coast to be its exclusion zone. It instructed ships headed for non-Iranian ports to sail west of this line.^[8] While Iran also did not designate any safe passages in its exclusion zone, this was unnecessary. Iran's exclusion zone allowed for ships to enter and exit the Gulf, and essentially only kept such foreign ships out of its own waters.^[10] Iran's exclusion zone made it easier for Iraq to target Iranian ships. It allowed Iraq to assume that any ship in Iran's territorial waters must be going to (or coming from) an Iranian port.^[11]

War studies scholar Stephen Phillips writes that "In January 1987, the Kuwaiti government proposed a clever scheme to deter Iranian attacks against their shipping. They asked the United States if they could reflag Kuwaiti tankers as American and receive the protection of the U.S. Navy. The administration of President Ronald Reagan debated this idea but finally agreed to it on March 7, 1987."^[12] These are known to O'Rourke as "reflagged Kuwaiti ships". On 17 May 1987, 37 US sailors were killed in an Iraqi aircraft attack on the USS Stark. Iraqi president Saddam Hussein apologized, saying that the pilot had mistaken the US vessel for an Iranian tanker.^[13]

United Nations Security Council Resolution 598, was adopted unanimously on 20 July 1987, which engendered Operation Earnest Will (24 July 1987 – 26 September 1988), a successful US effort to protect Kuwaiti merchandise and vessel, because as noted by O'Rourke: "Aside from Iranian shipping, the most frequent victims have been ships steaming under the world's predominant flags of convenience."^[1] Western-led convoy tactics with armed guard vessels were used for protection in the latter stages of the Tanker War.^[1] In 1987, the use of towed, radar-deflecting decoys and other passive countermeasures was successfully initiated.^[1]

In total, well over 100 sailors were killed and a similar number wounded.^[1] More than 30 million tons of cargo was damaged from 1981 to 1987.^[1] In 1987, during the conflict, Iran perfected the art of speedboat attacks, and concentrated "their fire on the crew compartments of their target ships."^[1] Iran also used Chinese-made shore-based Silkworm missiles to good effect.^[1]

• Boczek, Boleslaw Adam (1989). "Law of Warfare at Sea and Neutrality:Lessons from the Gulf War". Ocean Development and International Law. 20 (3): 239–271. doi:10.1080/00908328909545892.
• Dekker, Ige F.; Post, Harry H. G., eds. (1992). The Gulf War of 1980-1988: The Iran-Iraq War in International Legal Perspective. Dordrecht: Martinus Nijhoff. ISBN 0-7923-1334-8.
• Leckow, Ross (July 1988). "The Iran-Iraq Conflict in the Gulf: The Law of War Zones". International & Comparative Law Quarterly. 37 (3): 629–644. doi:10.1093/iclqaj/37.3.629.
• Silverstone, Paul H. (1984). "Naval Intelligence". Warship International. 21 (4): 396. JSTOR 44891106.
• Silverstone, Paul H. (1985b). "Naval Intelligence". Warship International. 22 (2): 145–146. JSTOR 44891147.
• Silverstone, Paul H. (1988a). "Naval Intelligence". Warship International. 25 (1): 37. JSTOR 44889197.
• Silverstone, Paul H. (1988b). "Naval Intelligence". Warship International. 25 (2): 195. JSTOR 44891248.
• Silverstone, Paul H. (1988c). "Naval Intelligence". Warship International. 25 (4): 402. JSTOR 44892028.
• Silverstone, Paul H. (1989). "Naval Intelligence". Warship International. 26 (1): 83. JSTOR 44892063.
• Zatarain, Lee Allen (2008). Tanker War: America's First Conflict with Iran, 1987–88. Casemate Publishers. ISBN 9781932033847.

• El-Shazly, Nadia El-Sayed (1998), The Gulf Tanker War: Iran and Iraq's Maritime Swordplay, Springer, ISBN 9781349263042
• Navias, Martin S.; Hooton, E. R. (1996), Tanker Wars: Assault on Merchant Shipping During the Iran-Iraq Crisis, 1980-88, Bloomsbury Academic, ISBN 9781860640322
• Silverstone, Paul H. (1985a). "Naval Intelligence". Warship International. 22 (1): 51. JSTOR 44888933.
• Silverstone, Paul H. (1985c). "Naval Intelligence". Warship International. 22 (3): 306. JSTOR 44891192.
• Silverstone, Paul H. (1985d). "Naval Intelligence". Warship International. 22 (4): 399. JSTOR 44891899.
• Silverstone, Paul H. (1986a). "Naval Intelligence". Warship International. 23 (1): 30. JSTOR 44894586.
• Silverstone, Paul H. (1986b). "Naval Intelligence". Warship International. 23 (2): 140. JSTOR 44889022.
• Silverstone, Paul H. (1986c). "Naval Intelligence". Warship International. 23 (3): 271. JSTOR 44891948.
• Silverstone, Paul H. (1986d). "Naval Intelligence". Warship International. 23 (4): 378. JSTOR 44889078.
• Silverstone, Paul H. (1987a). "Naval Intelligence". Warship International. 24 (1): 71. JSTOR 44889099.
• Silverstone, Paul H. (1987b). "Naval Intelligence". Warship International. 24 (2): 164. JSTOR 44894620.
• Silverstone, Paul H. (1987c). "Naval Intelligence". Warship International. 24 (4): 358. JSTOR 44891264.
• Walker, George K. (2000), "The Tanker War, 1980–88: Law and Policy", International Law Studies, 74, U.S. Naval War College
• Wang, Erik B. (1995). "The Iran-Iraq War Revisited: Some Reflections on the Role of International Law". Canadian Yearbook of International Law. 32.