Notwithstanding, Iran remains a leading state sponsor of terror through many platforms and methods.
The Trump administration said on Tuesday it was launching an inter-agency review of whether the lifting of sanctions against Iran was in the United States' national security interests, while acknowledging that Tehran was complying with a deal to rein in its nuclear programme.
And he said President Donald Trump has ordered an interagency review to figure out if continuing to lift sanctions against Iran is "vital" to the national security interests of the U.S.
The pivotal deal between Iran and six major powers restricts Tehran's nuclear program in exchange for the lifting of global oil and financial sanctions against the Islamic Republic.
The Joint Comprehensive Plan of Action, known more commonly as "the Iran deal", was the result of negotiations between former President Barack Obama, members of the United Nation's Security Council, Germany, and the EU.
Tillerson made his statement to Congress as part of an announcement that Iran had been found compliant with its end of the deal through April 18, a certification that must be made every 90 days.
"When the inter-agency review is completed, the administration looks forward to working with Congress on this issue", Tillerson said. Last month Secretary of Defense James Mattis called Iran the "world's biggest sponsor of state terrorism".
Though there was no sign the Trump administration meant to walk away from the deal, Tillerson twice cautioned that if left unchecked Tehran could become a threat like North Korea, which is also under pressure over its nuclear ambitions.
Iran was exempted from an OPEC deal to reduce output by 1.2 million barrels per day starting January 1, a victory for Tehran which argued it needs to regain the market share it lost during long years of sanctions. It is the first such notification under the Trump administration.
As CNN notes, if the US were to reapply sanctions against Iran, it would go against the terms of the JCPOA.
The European Union's foreign policy chief, Frederica Mogherini, said last month after meetings with senior Trump administration officials she was reassured in the talks that the U.S. was committed to fully implementing the deal.