US President Donald Trump has reportedly tasked a group of his trusted staffers to find a way to decertify the Iran nuclear deal after he was frustrated with his Secretary of State Rex Tillerson in this regard.

Trump assigned the group of his staffers this week, giving them a task to ensure there will not be a repeated certification of the Joint Comprehensive Plan of Action (JCPOA) in the next 90 day review, Foreign Policy reported on Friday citing a source close to the White House.

After hours of intense talks with his top national security advisers, Trump finally agreed on Monday to certify once again that Iran is complying with the deal, which he repeatedly denounced.

The nuclear deal, which was reached between Iran and world powers in 2015, put limits on Iran's nuclear activities in exchange for, among other things, the removal of all nuclear-related bans against the Islamic Republic.

The agreement is being reviewed by the US State Department every 90 days to declare whether Tehran was abiding by it.

Trump has assigned White House staffers with the task of preparing for the possibility of decertification for the 90-day review period that ends in October, the source added.

The report explained that there won't be any more details about the new assignment until after the first meeting, which is likely scheduled for early next week.

Trump had previously tasked Tillerson and the State Department with making a case for decertification of the deal -- which the sources said they failed to do.

Tillerson did not do this, and Trump is infuriated, said the source. He can't trust his secretary of state to do his job, so he is turning to the few White House staffers he trusts the most.

It was not only Tillerson who argued to certify the Iran deal. US Defense Secretary James Mattis, National Security Advisor H.R. McMaster, and the chairman of the Joint Chiefs of Staff, Gen. Joseph Dunford, also believed in Tehran compliance with the agreement.

A third source also explained that the president was frustrated that Tillerson told him that he had no choice but to confirm Iran was in compliance.

The president kept demanding why he should certify, and the answers Tillerson gave him infuriated him, said one of the sources.

All other parties to the deal -- China, France, Germany, Russia, and the United Kingdom as well as the International Atomic Energy Agency (IAEA) -- so far agreed that the deal is working as intended.