As President Donald Trump floats “regime change” in Tehran, previous U.S. attempts to remake the Middle East by force in recent decades can offer stark warnings about the possibility of a deepening involvement in the Iran-Israeli conflict.

"People want regime change," said Mariam, a pensioner, as she collapsed into the back of a taxi with her husband. The couple had just dragged their heavy suitcases across a bridge over the fast-flowing Aras River that marks Iran's remote northern border with the small nation of Armenia,