President Donald Trump on Monday vowed that any attack by Iran would be met with a response '1,000 times greater in magnitude,' after reports that Iran planned to avenge the killing of top general Qasem Soleimani.
A US media report, quoting unnamed officials, said that an alleged Iranian plot to assassinate the US ambassador to South Africa was planned before the presidential election in November.
'According to press reports, Iran may be planning an assassination, or other attack, against the United States in retaliation for the killing of terrorist leader Soleimani,' Trump tweeted.
'Any attack by Iran, in any form, against the United States will be met with an attack on Iran that will be 1,000 times greater in magnitude!'
Iran warned the US not to make a 'strategic error' on Tuesday following the president's remarks.
'We hope that they do not make a new strategic mistake and certainly in the case of any strategic mistake, they will witness Iran's decisive response,' government spokesman Ali Rabiei said.
The alleged plot to attack the US has been detailed in intelligence papers which have been seen by US intelligence and government officials.
American officials said they had been made aware of threats towards ambassador, Lana Marks, 66, since the spring but the intelligence detail has suddenly become more specific in recent weeks.
The Iranian embassy in South Africa's capital, Pretoria, is said to be involved in the plot according to Politico.
In January, a US drone strike killed Soleimani in Baghdad. At the time, Secretary of State Mike Pompeo said the US killed Soleimani to re-establish a deterrent against Iran.
Soleimani led the Quds Force, a unit of Iran's Islamic Revolutionary Guard Corps that oversees much of the country's military activities outside its borders.
Americans blame him for the death of numerous US troops in the region.
After Soleimani's killing, Trump noted that the general had been plotting to attack American diplomatic missions.
'They were looking to blow up our embassy,' Trump said in January, later revealing, 'I can reveal I believe it probably would've been four embassies.'
Relations between Washington and Tehran have been tense since the Iranian revolution, and have spiraled since Trump unilaterally pulled out of a landmark international nuclear deal with Iran in May 2018.
Additionally, Washington is pushing to extend an arms embargo on Iran that starts to progressively expire in October as well as reimposing UN sanctions on the Islamic republic.
The Iranian navy last week said it drove off American aircraft that flew close to an area where military exercises were underway near the Strait of Hormuz.
The military said three US aircraft were detected by Iran's air force radars after they entered the country's air defense identification zone.
General Kenneth McKenzie, the head of U.S. Central Command, has said that he had been expecting a 'response' from Iran over the US's presence in Iraq.
'I do not know what the nature of that response will be, but we will certainly be ready for it, should it occur,' he said.
Last Wednesday, McKenzie confirmed plans to cut the U.S. troop presence in Iraq from 5,200 to 3,000 by the end of September.
It's not known why the Iranians would want to target Marks but it is likely her long-standing friendship with Trump is a reason and would make the attack on her life all the more personal.
Marks, who has known Trump for more than 20 years and is a member of his Mar-a-Lago, became the US ambassador last October.
Before becoming a diplomat, Marks was best known for her six-figure handbags, clutched by A-list celebrities like Charlize Theron, Angelina Jolie and Kate Winslett.
Intelligence officials have also suggested that carrying out an attack in South Africa could be easier than targeting American diplomats in other parts of the world where improved relationships between the US and local police and national intelligence services could see an attack foiled.
© Associated Newspapers Ltd.