[From the description of their actions, they sound less like common thieves and more like agents of espionage. . .]
Very possible. Rather than cash they may have been after passports, drivers licenses, credit cards, and other ID to help establish false identities.
“Rather than cash they may have been after passports, drivers licenses, credit cards, and other ID to help establish false identities.”
If you have the resources of a nation at your disposal, which you would if you were an espionage agent, then getting somebody’s ID is not necessary. A nation can buy a birth certificate from any compromised clerk of the thousands of clerks in America. (Chicago or Detroit would be the places to start.) They can use an interconnected bank to establish real credit cards and real bank accounts. They can set up phony companies in foreign countries to establish legitimate links to US companies and thereby provide legitimate reasons to travel. (James Bond worked for Universal Exports.)
Iran may seem as though it is run by Larry, Moe and Curly, but their espionage agents were trained by the bad-asses of evil worldwide.