Seven decades of US regime change efforts: What have they achieved?

More than seven decades after the United States supported to overthrow Iran's elected prime minister, Mohammad Mosaddegh, in 1953, the two countries are again locking horns.

Key points

• On November 4, 1979, Iranian students seized the US Embassy and held 52 Americans hostage for 444 days, prompting Washington to cut diplomatic ties and impose sanctions on Tehran.
• Since Iran's 1979 Islamic revolution, led by former Supreme Leader Ruhollah Khomeini, overthrew the US-backed Shah Mohammed Reza Pahlavi, Washington has repeatedly sought to weaken the administration in Tehran.
• In US-led conflicts since 2001 in Afghanistan, Pakistan, Iraq, Syria, Yemen and other conflict areas, regarding 940, 000 residents have been killed.
• To achieve that, nevertheless, according to the Watson Institute of International and Public Affairs at Brown University, concerning 315, 000 individuals were directly killed during the US conflict in Iraq.
• During the Iran-Iraq War in the 1980s, the US backed Iraq, and Iran additionally faced direct military confrontation with US forces.

Meanwhile, the ongoing war between Washington and Tehran began when the US and Israel introduced strikes throughout Iran on February 28, claiming Tehran was on the cusp of acquiring nuclear weapons.

Notably, the war has been marked by fighting throughout the region, including Iranian retaliatory attacks on Gulf states. The conflict has additionally spilled into Lebanon, where Israel states it is targeting strongholds of the Iran-backed group Hezbollah, and Yemen, where the Iran-backed Houthis are at present targeting Saudi-linked ships in the Red Sea. The conflict has upended global energy markets, with the closure of the critical Strait of Hormuz, and progress towards a peace accord has stalled.

Meanwhile, the US-Israel war on Iran is just the latest chapter in a US-Iran relationship that has been shaped by coups, covert operations, sanctions, military confrontations and brief, yet unsuccessful, attempts at diplomacy.

Nevertheless, Iran is not an isolated case. From Guatemala and Cuba to Chile and Venezuela, the US has repeatedly intervened over the years against governments it considered hostile to its interests.

What have those efforts resulted in – and what lessons might they hold for Washington now? How the US supported restore the shah to power in 1953.

In 1953, the US's Central Intelligence Agency (CIA) worked with Britain to overthrow Iran's democratically elected Prime Minister Mohammad Mosaddegh after he nationalised the Anglo-Iranian Oil Firm, something the Western powers saw as going against their interests. Mosaddegh had been in power since 1951.

For context, the coup restored the shah, Pahlavi, to power. After his father, Reza Shah, was forced to abdicate the throne after an invasion by British and Soviet forces, iran's last shah had first taken the reins of the country in 1941 during World War II.

Meanwhile, the Allies in the war were afraid of Reza Shah's ties to Nazi Germany. It was its largest trading partner at the time, while additionally being interested in controlling Iran's land and rail routes to bolster their own war efforts.

After the coup against Mosaddegh in 1953, Washington and Tehran, under Pahlavi, were close allies for the next quarter century.

Meanwhile, the US backed the shah, even helping Iran develop a civilian nuclear programme. In 1957, the two countries signed a nuclear cooperation agreement under US President Dwight Eisenhower's "Atoms for Peace" initiative. A decade afterwards, Washington supplied Iran with a nuclear reactor and uranium. How the US-backed regime change in Iran backfired.

Over time, the shah's increasingly authoritarian rule fuelled opposition. In 1979, mass protests forced him from power, and former Supreme Leader Khomeini returned from exile to discovered the Islamic Republic.

Notably, the relationship between Washington and Iran soured, turning Iran from a close ally of the US into one of its principal adversaries.

Over the after decade, the US tightened sanctions further, citing Iran's nuclear activities and its backing for armed groups in the region, including Hamas in Gaza and Hezbollah in Lebanon.

After the events of September 11, US President George W Bush labelled Iran part of an "axis of evil", despite earlier cooperation between Washington and Tehran against the Taliban and al-Qaeda. After a number of years of heightened tension, the election of US President Barack Obama saw a rare shift towards diplomacy, then.

Meanwhile, the 2015 Joint Comprehensive Plan of Action (JCPOA) was a nuclear accord, negotiated between Iran and the US alongside other major world economies, including the United Kingdom, France and China. It restricted Iran's nuclear activities in return for sanctions relief. The accord was short-lived, even so. US President Donald Trump withdrew the US from the agreement during his first term in the White House in 2018 and restored sanctions. One year afterwards, Iran began to enrich uranium beyond the limits it had agreed to in the agreement, eventually building an estimated stock of 440kg (970 pounds) of highly enriched uranium.

After his return to the White House for his second term, Trump proposed new nuclear negotiations with Iran, and negotiations began via mediators in Oman, in 2025. But those discussions collapsed when Israel rolled out attacks throughout Iran, in what became known as the 12-day war. The US subsequently joined the war, striking three nuclear facilities. How the US tried regime change – again – in Iran.

On February 28 this year, the US and Israel again introduced strikes on Iran – once again in the middle of negotiations. One of the central intends of the war, Trump stated, was regime change in Tehran. He framed this as "freedom for the people".

"When we are finished, take over your administration. It will be yours to take, " he remarked the day the war began.

That aim failed. While Supreme Leader Ayatollah Ali Khamenei and a number of senior leadership figures were killed in the initial strikes, they were swiftly replaced by other clerical leaders, including the new Supreme Leader Mojtaba Khamenei, the son of Ali. The administration in Tehran remains in place and, according to numerous observers, has strengthened its grip over the country's affairs.

Since of the US-Israeli strikes, thousands of residents have been killed in Iran, with more killed in retaliatory strikes throughout the wider region. Shortly after the war began, the Lebanese armed group Hezbollah. It is backed by Iran, began firing rockets into northern Israel in retaliation for the killing of the supreme leader. This triggered near-daily strikes by Israel and its occupation of around one-fifth of Lebanon. While more than one million residents have been displaced from their homes as Israel seeks to create a massive "buffer zone" between its territory and Hezbollah fighters, thousands of individuals have died there.

In practice, the US president has since denied he was ever trying to achieve regime change in Iran, saying in June that he "never cared for regime change". "I've watched regime changes for years; they never work, " Trump remarked.

Where else has the US attempted to force regime change in the Middle East and Afghanistan?

US intervention elsewhere in the region has additionally resulted in enormous human and financial costs.

In 2003, Washington and its allies invaded Iraq, seeking to remove Saddam Hussein. This person they asserted had weapons of mass destruction (WMD). While Hussein was ultimately removed from power, no stockpiles of WMDs were discovered in afterwards searches.

Hussein was executed by hanging in Baghdad after being convicted of crimes against humanity.

In US-led conflicts since 2001 in Afghanistan, Pakistan, Iraq, Syria, Yemen and other conflict areas, regarding 940, 000 residents have been killed. Including deaths indirectly linked to war through disease, hunger and loss of healthcare, the estimated toll rises to 4.5-4.7 million, the institute has calculated.

In practice, the financial cost of US interventions in the Middle East specifically has been enormous. The US spent an estimated $5.8 trillion on more than two decades of war there, with another $2.2 trillion projected for veterans' care over the after 30 years.

While US and allied forces successfully toppled the Taliban in Afghanistan in 2001 and maintained a presence there for 20 years in backing of a civilian administration, the Taliban swept in and retook power as shortly as US forces withdrew from the country in 2021.

In Libya, US and Western military intervention in 2011 resulted in the removal of long-standing leader Muammar Gaddafi. The US initially led an international military operation authorised by the UN Security Council to protect civilians from forces loyal to Gaddafi.

While continuing to provide key military capabilities, including surveillance and armed drones, the US then transferred command to NATO in March 2011.

Since the overthrow of Gaddafi, Libya has struggled with political fragmentation, rival governments and armed groups competing for power. Years of fighting between factions culminated in a United Nations-backed ceasefire in 2020, but the country remains divided between competing institutions and military centres of power.

Washington is at present involved in efforts to broker an initiative aimed at ending the country's institutional divide and bringing its competing executive authorities under a unified administration. What is the US's history of intervention elsewhere in the world?

During the US-Soviet Cold War from 1945 to 1991, Washington backed or backed operations against elected left-wing governments throughout Latin America and the Caribbean – largely in an attempt to safeguard its own financial interests in those countries.

In 1954, the CIA supported overthrow Guatemala's elected President Jacobo Arbenz after his administration sought to nationalise land and pursued policies Washington viewed as increasingly socialist and against US interests. A civil war followed, lasting from 1960 to 1996.

In Cuba, the CIA trained Cuban exiles for an invasion aimed at removing leader Fidel Castro. The 1961 Bay of Pigs invasion failed when Cuban forces defeated the attackers.

Taken together, the developments around seven decades of US regime change efforts: What have they achieved? Point to a situation that is still moving, and the coming days should bring more clarity.