The targeted killing of Iranian Maj-Gen Qassem Soleimani by US forces represents just the latest escalation in Donald Trump's long-running campaign to contrast himself with his predecessor by taking an increasingly aggressive posture towards Tehran.

Mr Trump took office in 2017 having promised to pull the US out of the 2015 Joint Comprehensive Plan of Action, the agreement between Iran, the EU, and the five permanent members of the UN Security Council.

The agreement, which limited Iran's ability to enrich nuclear materials to weapons grade for 10 years, was widely seen as one of former president Barack Obama's major foreign policy accomplishments.

While many of Mr Trump's closest advisers — including former secretary of defence James Mattis and former secretary of state Rex Tillerson — counselled him against pulling out of an agreement with which Iran was judged to be in compliance, the president ignored his advisers by refusing to certify Iran's compliance in October 2017. In May 2018 he declared that the US would withdraw from the deal, and by the end of 2018 both Mattis and Tillerson had left government service.

Mr Trump and his administration have since embarked on what he has called a “maximum pressure” campaign akin to the regime of increasingly crippling sanctions which led to his first meeting with North Korean dictator Kim Jong-un, and has routinely spread misinformation about the actions taken by Mr Obama to curb Iran's nuclear ambitions, such as falsely claiming that his predecessor — who he repeatedly accused of being a secret Muslim who was not born in the United States — bribed Iran by settling a long-running legal dispute over a refund for military equipment purchased by the previous government of Iran.

Tensions high as Trump approves new Iran sanctions: In pictures Show all 17 1 /17 Tensions high as Trump approves new Iran sanctions: In pictures Tensions high as Trump approves new Iran sanctions: In pictures Iran claims that in this picture released by Iran state TV, their surface-to-air missile is seen as it shoots down a US surveillance drone EPA Tensions high as Trump approves new Iran sanctions: In pictures This photo shows US RQ-4A Global Hawk unmanned surveillance drone. A drone of this model was shot down by Iran on Thursday 21 June AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures An oil tanker is on fire after it was subject to a suspected attacked at the Gulf of Oman on June 13. The US has blamed Iran for the attack Reuters Tensions high as Trump approves new Iran sanctions: In pictures Iran claims that in this picture released by Iran state TV, debris from the downed US drone is seen after it was recovered from Iranian waters AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures Smoke billows from an oil tanker after it was subject to a suspected attacked at the Gulf of Oman on June 13 Reuters Tensions high as Trump approves new Iran sanctions: In pictures US President Trump holds up a signed executive order to increase sanctions on Iran on 24 June AP Tensions high as Trump approves new Iran sanctions: In pictures Iranian President Rouhani stated in a televised address that the White House is "afflicted by mental retardation" following the increase in sanctions on 25 June EPA Tensions high as Trump approves new Iran sanctions: In pictures An Iranian navy boat tackles the fire on the Norwegian owned Front Altair oil tanker after it was hit in a suspected attack AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures Iran claims that in this picture released by Iran state TV, debris from the downed US drone is seen after it was recovered from Iranian waters AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures Smoke billows from an oil tanker after it was subject to a suspected attacked at the Gulf of Oman on June 13 Reuters Tensions high as Trump approves new Iran sanctions: In pictures A screenshot from a video released by the US Department of Defense that the US claims to show Iranian removing an unexploded limpet mine form the hull of the Japan-owned ship that was attacked in the Gulf of Oman on June 13 Getty Tensions high as Trump approves new Iran sanctions: In pictures An item reportedly found on the Japan-owned oil tanker that was attacked on June 13 in the Gulf of Oman AFP/Getty Tensions high as Trump approves new Iran sanctions: In pictures A handout photograph from the US Department of Defense shows a composite material that the US claim was left behind on the hull of the Japan-owned oil tanker following the removal of an unexploded limpet mine Getty Tensions high as Trump approves new Iran sanctions: In pictures A view from the cabin of an Iranian navy boat as it tackles the fire on the Norwegian owned Front Altair oil tanker after it was hit in a suspected attack EPA Tensions high as Trump approves new Iran sanctions: In pictures Release by US government A picture released by U.S. Central Command shows damage to the hull of the oil tanker Kokuka Courageous. The picture suggests that the ship is 'likely' to have been hit by a mine as the US Secretary of State Mike Pompeo moves to blame Iran for the suspected attack Reuters Tensions high as Trump approves new Iran sanctions: In pictures Smoke billows from an oil tanker after it was subject to a suspected attacked at the Gulf of Oman on June 13 Reuters Tensions high as Trump approves new Iran sanctions: In pictures Release by US government A picture released by U.S. Central Command shows damage to the hull of the oil tanker Kokuka Courageous. The pictures suggests that the ship is 'likely' to have been hit by a mine as the US Secretary of State Mike Pompeo moves to blame Iran for the suspected attack EPA

Most of the other permanent UNSC members, however, have opposed the US withdrawal and, led by French president Emmanuel Macron, have endeavoured to keep Iran at the negotiating table even as Tehran has retaliated against US sanctions by restarting uranium enrichment.

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Additionally, Mr Trump in April took the unprecedented step of declaring Iran's Islamic Revolutionary Guard Corps — the branch of Iran's military to which Soleimani belonged — a terrorist organisation over the opposition of the Pentagon and CIA. The IRGC Quds Force, which Soleimani led, had been a designated terrorist organisation since 2007.

It was the latter group's designation which figured prominently in a Defence Department statement taking responsibility for the death of Soleimani.