Like porcupines colliding in the dark, the United States and Iran each believe they are victims of the other’s aggression.

Real porcupines no doubt take care to avoid painful nocturnal encounters, but such good sense cannot be guaranteed when it comes to U.S. President Donald Trump and Iran’s Ayatollah Ali Khamenei.

Trump, whose Iran “policy” can flip-flop from belligerence to conciliation within a single news cycle, is the least predictable of the six American presidents who have had to grapple with the Islamic Republic, as well as one of the most obtuse.

Khamenei is just as obdurate and obsessed with resisting the “Great Satan” whatever the cost to his own people as his dour predecessor Ayatollah Ruhollah Khomeini, the architect of the 1979 Islamic Revolution.

The mutually demonising narrative nurtured by the United States and Iran has dominated their relations for the past four decades, despite periodic attempts at diplomacy that have never achieved a transformative breakthrough.

Bad blood

It’s worth looking at the history to understand why there is so much bad blood between the two countries.

High on Iran’s list of grievances is the 1953 coup orchestrated by U.S. and British intelligence to topple elected Iranian Prime Minister Muhammad Mossadegh, who had won popular acclaim for his drive to nationalise the country’s oil industry.

The coup effectively reinstated the Shah of Iran, who had been sidelined by Mossadegh. The Shah consolidated his power, launched reforms that infuriated the Shi’ite clergy, spent wildly on Western weaponry, forged ties with Israel and used his secret police to repress opposition. Khomeini denounced him as a U.S. puppet.

For much of the Cold War, Iran was the keystone of U.S. power in the Gulf region. But the United States could not save the Shah from the revolution that swept Khomeini to power on a wave of Shi’ite religious fervour and reshaped the Middle East.

For Americans, the Shah’s ouster was bad enough. But the storming of their Tehran embassy by Islamist protesters in November 1979 was a stark humiliation prolonged by the holding of American hostages there for 444 days.

Iranian memories are scarred by U.S. support for Saddam Hussein after his invasion of Iran in 1980 touched off an eight-year war that killed hundreds of thousands on both sides. Saddam had feared that Khomeini’s revolutionary ideology might spread to Iraq’s Shi’ite majority and threaten his Sunni-dominated regime.

While fighting for survival against Iraq, Iran hit back at the United States in Lebanon, where the militant forerunners of Hezbollah carried out suicide bombings that destroyed the U.S. embassy and a Marine barracks in 1983, killing 258 Americans as well as 46 Lebanese.

Arms for hostages

Iranian-backed Islamists and other groups kidnapped dozens of Americans and other foreigners in Lebanon in the years after Israel’s 1982 invasion. Even as it backed Iraq, the United States secretly sold weapons to Iran in 1985-86 to try and secure the release of its hostages in Beirut. The Reagan Administration then used the profits illegally to fund Contra guerrillas in Nicaragua – the so-called Iran-Contra scandal.

Iranians bitterly recall how the USS Vincennes missile cruiser shot down an Iran Air flight over the Gulf in 1988, killing all 290 people on board. The United States said its warship had mistaken the passenger plane for a military jet.

The incident occurred at the height of the “tanker war” in the Gulf. Iraq had tried to cripple Iran’s oil industry since 1983. In reprisal, the Iranians disrupted Gulf shipping with attacks on tankers, especially those of Saudi Arabia and Kuwait, which had bankrolled the Iraqi war effort. U.S. forces became directly involved after Washington let Kuwait re-register its tankers under the U.S. flag.

The September 11, 2001 suicide attacks on the United States by Osama bin Laden’s Sunni plane hijackers led to a short-lived U.S.-Iranian detente. Iran stood to gain by the U.S. war on bin Laden’s Taliban allies in Afghanistan, and Iranian diplomats helped broker a new Afghan government after the Taliban defeat.