As part of the legal framework surrounding the deal between Iran and the P5+1 countries, officially known as the Joint Comprehensive Plan of Action, the Secretary of State is required to report to Congress every 90 days, whether or not Iran is in compliance with the deal.

In April, he decided that certifying Iran as compliant with the deal was in the national security interest of the United States, and communicated this to House Speaker Paul Ryan (R-Wis.), but he did mention that the White House was reviewing policy on Iran and that he was unwilling to break the deal until the policy had been decided upon.

Three months later, with the review into foreign policy on Iran still not completed, four leading Republican Senators have written an open letter to Tillerson asking him to publically acknowledge that Iran has violated the deal.

Senators Tom Cotton (Ark.), Ted Cruz (Tex.), David Perdue (Ga.) and Marco Rubio (Fla.) wrote: “We believe that a change in that policy is long overdue. As we near the end of another 90-day review period, U.S. interests would be best served by a sober accounting of Iran’s JCPOA violations as well as the regime’s aggressive and destabilising behaviour.”

It details a long list of Iran’s violations of the deal, including carrying too much heavy water (a material used in the production of nuclear materials) and the operation of advanced centrifuges, and the behaviour of the Iranian Regime which leads the Senators to believe that the Regime is not holding off on their development of nuclear weapons.

In the letter, the four Senators argue that it is in the national interest of the US to increase pressure on Iran before they have nuclear weapons.

It read: “Iran continues to wage a campaign of regional aggression, sponsor international terrorism, develop ballistic missile technology, and oppress the Iranian people. Iran’s aggression directly targets the United States. In light of these actions, there is simply no basis on which to make a certification that U.S. national security is bolstered by continued sanctions relief. In fact, a continuation of the current policy would be tantamount to rewarding Iran’s belligerence.”

If Tillerson admitted that Iran was in violation of the nuclear deal, it doesn’t necessarily mean that the deal would automatically collapse but it would provide leverage on the Iranian Regime.