While the US kept in place most sanctions against Tehran, China and Russia - along with many European countries - had begun reaping the benefits of trade with an Iran eager to do business with the world.
Now, President Trump is threatening sanctions against any country that continues to do business with Iran. But will his attempt to restore the status quo before the Iran deal really work?
Even if the Europeans cave in to US demands, the world has changed a great deal since the pre-Iran deal era.
President Trump is finding that his threats and heated rhetoric do not always have the effect he wishes. As his Administration warns countries to stop buying Iranian oil by November or risk punishment by the United States, a nervous international oil market is pushing prices ever higher, threatening the economic prosperity he claims credit for. President Trump's response has been to demand that OPEC boost its oil production by two million barrels per day to calm markets and bring prices down.