It’s possible the Iranians will have been accused of violating the deal by the time a new president takes office, so a review could tally those transgressions to sow doubts in the minds of the American public about the soundness of the agreement. Depending on how major the violations are, the U.S. might also be able to convince other nations that the deal isn’t working.
Even if the Iranians haven’t committed any or many notable violations, there are other factors a president could point to.
Take the regional situation: If Iran, either directly or through proxies, has escalated its interference in other countries in the Middle East, a president could blame the nuclear deal by saying it has given Tehran economic leverage to pursue mischief outside its borders. America’s Arab allies, who have watched Iran make inroads everywhere from Syria to Lebanon to Iraq, have long argued that the Iranian government will take advantage of sanctions relief to funnel more money toward its regional aggression.
Here, a U.S. president — and a hawkish Congress — also has the option of leveling new sanctions on Iran that aren’t necessarily tied to its nuclear program but rather to its support for terrorist groups. (Existing sanctions that target Iran over its support for terrorism and its abuses of human rights won’t be lifted under the nuclear deal.)