Mysterious attacks on oil tankers near the strategic Strait of Hormuz show how one of the world’s crucial chokepoints for global energy supplies can be easily targeted, 30 years after the U.S. Navy and Iran were entangled in a similarly shadowy conflict called the “Tanker War.”

While the current tensions are nowhere near the damage done then, it underscores how dangerous the situation is and how explosive it can become.

The so-called “Tanker War” involved American naval ships escorting reflagged Kuwaiti oil tankers through the Persian Gulf and the strait after Iranian mines damaged vessels in the region. It culminated in a one-day naval battle between Washington and Tehran, and also saw America accidentally shoot down an Iranian passenger jet, killing 290 people.

U.S. estimates suggest Iran attacked over 160 ships in the late 1980s confrontation.

“We need to remember that some 30% of the world’s crude oil passes through the straits,” said Paolo d’Amico, the chairman of the oil tanker association INTERTANKO. “If the waters are becoming unsafe, the supply to the entire Western world could be at risk.”

So far, six oil tankers have been damaged in suspected limpet mine attacks, explosives that can be magnetically stuck to the side of a ship. The first attack happened May 12 off the coast of the Emirati port city of Fujairah and targeted four tankers. Thursday’s apparent attack damaged two other tankers.

The U.S. has blamed Iran for both incidents, offering a video on Friday it said showed Iranian Revolutionary Guard forces spirit away one mine stuck to a tanker that didn’t explode in Thursday’s assault. For its part, Iran denies being involved and calls the allegations part of America’s “Iranophobic campaign” against it.

Meanwhile, the owner of the tanker Kokuka Courageous said its sailors saw “flying objects” before the attack, suggesting it wasn’t damaged by mines and contradicting the U.S. military.

Confusion pervaded the start of the “Tanker War” as well.

That conflict grew out of the bloody eight-year war between Iraq and Iran in the 1980s, which began when Iraqi dictator Saddam Hussein invaded Iran. The war killed 1 million people. The U.S. supported Saddam by providing intelligence, weaponry and other aid.

Iraq first targeted Iran’s shipping and by 1984 attacked Kharg Island, a crucial oil-tanker-loading terminal for Iran. Its air force also attacked ships in the Persian Gulf. After the Kharg attack, Iran began a concerted campaign to attack shipping in the region.

Iraq ultimately would attack over 280 vessels to Iran’s 168, according to the U.S. Naval Institute.

The Iran’s mining campaign began in earnest in 1987. At night, the Revolutionary Guard would drop mines from vessels disguised as traditional dhows, which ferry cargo around the waters of the Persian Gulf.

As attacks targeted Kuwaiti oil tankers, the U.S. ultimately stepped in to protect them. The Soviet Union also volunteered.

While mines represented a small number of the attacks, their psychological impact grew. They also allowed Iran to attack its foes without having to take direct responsibility.

The mines were described as “God’s angels that descend and do what is necessary,” by Akbar Hashemi Rafsanjani, who would later become president of Iran.

Analysts say use of naval mines and bombs is a trend that continues today.

“Iran’s strategy at sea particularly is based on disruption,” said Dave DesRoches, a professor at the Near East South Asia Center for Strategic Studies at the National Defense University in Washington. “They know they can’t dominate. They have to disrupt.”

Ultimately, the U.S. tied Iran to the mining when it captured the Ajr, an Iranian ship loaded with mines in 1987. When the USS Samuel B. Roberts struck a mine and nearly sank the next year, the Navy matched it to those seized from the Ajr.

The attack on the Roberts sparked a daylong naval battle between Iran and the U.S., known as Operation Praying Mantis. American forces attacked two Iranian oil rigs and sank or damaged six Iranian vessels.

Several months later, tragedy struck. The USS Vincennes, after chasing Guard vessels into Iranian territorial waters, mistook an Iran Air commercial jetliner for an Iranian F-14, shooting it down and killing all 290 people onboard.

Thirty years later, events of the “Tanker War” still resonate in Iran.

A recent billboard put up in Tehran’s Vali-e-Asr Square shows U.S. and Israeli ships afire and sinking, with captions in English, Farsi, Arabic and Hebrew reading: “We Drowned Them All.”

While the billboard is meant to show support for the Palestinians — it prominently features Jerusalem’s al-Aqsa Mosque — it came just days after the Fujairah attack.

Around this time as well, Supreme Leader Ayatollah Ali Khamenei gave an address to university students, who gave him a portrait of Nader Mahdavi, a Revolutionary Guard soldier killed in a U.S. attack amid the “Tanker War.”

“The supreme leader asked whose picture it was and I replied, ‘Mahdavi,’” the semi-official ANA news agency quoted the student who gave the portrait to Khamenei as saying. “The supreme leader smiled and said, ‘Excellent, very timely.’”