Tillerson noted that President Donald Trump may not continue to withhold USA sanctions against Iran, despite its compliance, because of its destabilizing role as terror sponsor across the Middle East: "Iran remains a leading state sponsor of terror through many platforms and methods", he wrote.
However, in a letter to Speaker of the House Paul Ryan sent late Tuesday, Secretary of State Rex Tillerson says the administration has undertaken a full review of the agreement to evaluate whether continued sanctions relief is in the national interest.
Notwithstanding, Iran remains a leading state sponsor of terror through many platforms and methods.
The 2015 deal between Iran and six major powers restricts Tehran's nuclear program in exchange for the lifting of worldwide economic sanctions against the Islamic Republic.
After the International Atomic Energy Agency verified in January of 2016 that Iran was in compliance with terms to scale back its nuclear programme, some international sanctions were lifted.
Votel said that, since the agreement was finalized, the US military has seen a heightened number of "malign activities" on the part of Iran and its proxies in the Central Region, including "Iraq, Syria, Afghanistan, Pakistan, Yemen, Egypt, the Sinai, and the Bab-el-Mandeb Strait [located between Yemen and Djibouti and Eritrea] and in other parts of our area of responsibility".
As part of the so-called "joint comprehensive plan of action" (JCPOA), the State Department must notify Congress every 90 days on Iran's compliance with the terms of the deal.
Defense Secretary James Mattis said last month that Iran continues to export terrorism and sponsor the activity of its ally Hezbollah, a Lebanon-based terrorist group. Tuesday's was the first update for the Trump administration. Congress has already passed bills extending sanctions against Iran, while the US Treasury has announced further sanctions against those closely linked to Iran's Islamic Revolutionary Guard Corps (IRGC) and its clandestine network of global operatives.
Trump has repeatedly expressed his disdain for the agreement.
On Monday a senior White House official told Foreign Policy that the administration is leaning toward adopting "more rigorous application of the tools at its disposal" on Iran.