Iran’s supreme leader Ayatollah Ali Khamenei has lashed out at President Trump, accusing him of being a “foul-mouthed retard.”

Following Trump’s refusal to recertify Iran’s nuclear deal with the U.S., Khamenei penned a scathing rant on his website, labelling Trump as “foul-mouthed”, uttering “nonsense,” and “suffering from retardation”.

“The President of the United States displays nonsense; however, this should not lead us to ignore the mischief of the US regime,” Khamenei said on his website.

Rt.com reports: Khamenei declined to comment on Trump’s “irrational behaviour towards Iran,”  saying that it would be “a waste of time to respond to such blatherings and nonsensical remarks by the foul-mouthed US President.”

The supreme leader claimed that the US President and his team were “suffering from retardation because they do not understand the developments in Iran and the region.”

Last week, the US President proceeded with his disavowal of the Iran deal, also known as the Joint Comprehensive Plan of Action (JCPOA), and refused to recertify Tehran’s compliance with the agreement. Later, Trump added that there was “a very real possibility” that the deal would be terminated altogether.

Khamenei said that the pact “serves its interests.”

“We will not tear up the deal before the other party does: if they tear up JCPOA, we shred it,” he cautioned.

The supreme leader went on to urge the European nations that are also signatories to the agreement “to stand up against the US measures” such as sanctions, which “they anticipate to emerge from Congress.”

Trump referred the matter to American lawmakers, who have 60 days to decide whether to re-impose sanctions on Tehran, which were lifted in exchange for capping its nuclear program under the deal.

“They want to take back young, faithful and developed Iran to 50 years ago,” Khamenei added, saying that this was not possible.

“Due to backwardness, they are incapable of understanding this reality, and for this reason they have made a miscalculation and suffered, and will suffer successive defeats at the hands of the Iranian nation,” the supreme leader continued, noting that Washington was “furious” at Iran for thwarting its “plots” in Syria, Lebanon and Iraq, according to Press TV.