In some ways, attempting to employ Latin American criminals to carry out a terrorist act is the worst case scenario, but this case also shows how US-Mexico cooperation can stymie such actions.
The FBI charged two men, one tied to the Iranian IRGC's Qods force, with plotting to blow up a restaurant in Washington, D.C., in order to assassinate the Saudi ambassador to the US. One of the men attempted to contact a Mexican criminal organization (likely the Zetas) to pull off the job, but ended up meeting with DEA sources posing as cartel members instead. There were discussions of other potential attacks including some against the Saudi and Israeli embassies in DC. However, the killing of the Saudi ambassador seems to have been their main focus and they actually went through with wiring $100,000 to the source as a down payment for the attack.
Some initial comments and analysis below:
1. There are questions about how high up in the Iranian government this plot went and it seems uncharacteristically bold for Iran to act on US soil, but let's be clear that this was a real plot. The evidence is rather clear that officials within Iran's Qods force were involved, approved the operation, assisted in sending money, pressed for their US contact to work faster, and are now being sanctioned by the US government.