As part of his push to revisit the 2015 nuclear deal later this week, US President Donald Trump is expected to unveil a broader plan to roll back Iranian influence across the Middle East.
Former US diplomats posted to the region, however, are deeply skeptical that the United States can come out ahead in a geopolitical confrontation with Tehran. While the White House has expressed frustration with the gains made by Iran-backed Shiite groups in places such as Iraq, Syria and Yemen, three US ambassadors warned that changing the situation on the ground would be costly and difficult to achieve.