President Trump speaks during a news conference with Italian Prime Minister Paolo Gentiloni in the White House.
"It was a awful agreement", said Trump, who has regularly blamed his predecessor Barack Obama for securing it. "It shouldn't have been negotiated the way it was negotiated".
US Secretary of State Rex Tillerson reiterated during a press conference on Wednesday that "the Trump administration is now conducting across the entire government a review of our Iran policy".
Trump's administration has been publicly tightening the noose on Iran over the deal, which was negotiated by the five permanent UN Security Council members plus Germany to roll back Tehran's nuclear programme in return for the easing of sanctions.
Tillerson's announcement was the strongest signal to date that US President Donald Trump might walk away from the nuclear deal.
"The Iran nuclear deal is a bad one for the United States and the world".
"Not only does that defy logic - but it adversely effects American security interests", said Reza Marashi, National Iranian American Council.
The president said Iran is doing "a tremendous disservice" to the agreement that they signed.
The Obama administration insisted the provisions would slow the time it would take Iran to produce nuclear weapons.
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And shortly after the Italian prime minister said that a US role in Libya was critical, Trump, in response to a question about whether he believes his administration should play a part in helping to stabilize that country, said bluntly, "I do not see a role in Libya". In other areas, however, the Trump administration has appeared poised to take a far more aggressive line against Tehran.
"The contract to receive counselling on the redesign was negotiated and signed in Beijing on April 13", the Iranian Foreign Ministry said in a written statement to parliament.
However, calling Iran "a leading state sponsor of terror", Tillerson informed the Congress that the Trump administration had directed a full review of the 2015 nuclear deal to evaluate whether continued sanctions relief was in the USA national security interests. Critics have said it's unfathomable that the US would grant sanctions relief to Tehran even as Tehran continues testing ballistic missiles, violating human rights and supporting extremist groups elsewhere in the Middle East. "Iran's provocative actions threaten the United States, the region, and the world", Tillerson said.
The certification of Iran's compliance, which must be sent to Congress every 90 days, is the first issued by the Trump administration.
"This deal represents the same failed approach of the past", Tillerson said on Wednesday at a hastily arranged news conference in Washington.
Tillerson, during the press briefing, had also described Tehran as a "leading state sponsor of terror".
"Of course one of the greatest threats we face is the rise and fall of terrorism", he said.
After he was elected, some of his top officials - including his defense secretary, James Mattis - said it would be unwise to scrap the deal.