Bangladesh, Aug. 29 -- The latest round of US sanctions against Iran marks an important evolution in Washingtons long-running campaign of “maximum pressure.” Rather than focusing exclusively on senior Iranian officials, military institutions and strategic sectors, the new measures place greater emphasis on the international networks that allow Tehran to sell oil, move money, evade restrictions and finance its regional partners.

That distinction matters. Iran has lived under extensive American sanctions for decades and has demonstrated a remarkable capacity to adapt. When one route for exporting oil is closed, another emerges. When a bank becomes inaccessible, intermediaries and informal financial channels take its place. When...