Iran watchers are wary that President-elect Joe Biden may dive head-first into rejoining the Iran nuclear deal and squander the leverage created by his predecessor’s tough policies that kept Iran’s regional aggression in check in recent years.

“What we saw from 2013, when the initial agreement was signed … and 2018, when the Trump administration broke out, was a massive expansion of Iranian activities, aggression, and expansion throughout the region,” said Ambassador James Jeffrey, President Trump’s former special envoy to the Global Coalition to Defeat ISIS.