Mr Trump said the 2015 nuclear deal negotiated by his predecessor, Barack Obama, was “an embarrassment” and hinted that he may not recertify the agreement when it comes up for a mid-October deadline.
He said: “I don’t think you’ve heard the last of it.”
The President called Iran an “economically depleted rogue state” that exports violence.
Mr Trump has already promised to withdraw the US from the historic Paris climate accord.
In an extraordinary speech to the international peace-keeping organisation, the Commander in Chief also said he would be forced to “totally destroy” North Korea if the rogue nation continued to develop nuclear weapons and threaten America.
More to follow.