US-Iran relations were at a historic peak in 2015 after the US joined six other nations in signing the Iran nuclear deal.
However, the ties started deteriorating again since US President Donald Trump took office, taking a dive five months ago when Trump withdrew from the nuclear deal.
Trump would often attack the 2015 deal while campaigning for his presidency, saying it would lead to a nuclear holocaust.
On May 8, he officially pulled out of the agreement, which brought tensions to a new high.
Iranian President Hassan Rouhani speaks during a press conference on the sidelines of the UNGA in New York, September 26, 2018. /VCG Photo
In response, Iranian President Hassan Rouhani railed against the move, calling it illegitimate and warning that Iran could resume enriching "limitless" amounts of uranium if the deal broke down.
To make matters worse, Trump re-imposed sanctions against Iran in August. An attack on a military parade in Iran left 25 dead last month.
Rouhani blamed the US and its Gulf states allies for the incident. The US denied the accusations, saying it condemns any terrorist attack.
Tensions kept worsening as the two leaders faced off later that week at the United Nations General Assembly.
They butted heads, with Trump calling for the isolation of Iran. Trump said the US asked all nations to isolate Iran's regime as long as its aggression continues.
Rouhani soon fired back, highlighting the strength of his country's people. But later, on the sidelines of the UNGA, the president said Iran does not want war nor to increase tensions.
He called on the US to follow international law, and respect national sovereignty. But with more planned US sanctions fast approaching, many fear the US may ignore Iranian calls.