In doing so, he has backed the position of Secretary of State Rex Tillerson, who is said to favor maintaining the nuclear agreement with Iran, albeit with some modifications to strengthen the current arrangement.
Tillerson's position echoes that of Trump's during the 2016 presidential campaign period. Both Trump and his campaign advisers argued that while they did not support the Iran deal, they would respect the fact that a deal had been made, and would instead seek to enforce it and renegotiate aspects of it. This position made Trump an outlier in the Republican field, with Paul as the only other candidate taking a similar stance.
According to a report by the Washington Free Beacon, Tillerson is at odds with UN Ambassador Nikki Haley, who favors a more hawkish stance of immediate withdrawal from the agreement, and reportedly "thinks that [Tillerson is] trying to undermine the president and preserve Obama's Iran legacy." Haley's stance lines up closely with that of Senators Marco Rubio (R-FL) and Ted Cruz (R-TX), whom she backed in last year's primary.