Trump is going to win the battle against the Mullahs in Iran, and this illustrates how he'll do it.

European companies are leaving the Islamic Republic of Iran in droves fearing U.S. sanctions after President Donald Trump’s decided to withdraw from the 2015 nuclear deal earlier this month. The regime in Tehran is “particularly concerned by the decisions of various European companies to halt their Iranian operations until the future of sanctions was clear,” several German newspapers reported on Monday.

“The cascade of decisions by EU companies to end their activities in Iran makes things much more complicated,” Iranian Foreign Minister said. The statement comes days after the French oil company Total pulled out $5 billion worth of investments from the country fearing U.S. sanctions.
The EU, backed by the governments of France and Germany, has been scrambling to save the European business interests in Iran. German and French companies had made huge investments in Iranian oil and industrial sectors since the nuclear deal eased sanction on the regime three years ago.

The Trump administration has made its intentions clear to go after any foreign player found guilty of sanctions-busting in Iran. “US withdrawal and new raft of sanctions will hurt a number of European firms with connections to Iran. Washington has threatened to hold anyone doing prohibited business in Iran to account.” Germany’s state-run DW News confirmed.

The US has far, far more economic leverage over the EU than Iran does.

This is why Trump also has enormous leverage in his negotiations with the mullahs.  Their regime is very brittle, and cannot withstand much more pressure.  Sending pallets of American taxpayer's cash helped them, but they've likely spent or embezzled it all by now, and military adventurism abroad and an angry, impoverished populace at home make for a difficult situation.  In other words, it's tailor made for forcing either an internal revolution or a far better agreement with the West over both their nuke program and their foreign meddling.

Keep in mind that this is also how Trump gets concessions from the Red Chinese.  Although not quite as brittle a government as the one in Iran, their existence is likewise dependent on a happy populace, and that in turn is dependent on their continued economic prosperity.  That prosperity is built on world trade.  As with Iran, if Trump can damage that, he'll seriously threaten the stability of the Communist regime in mainland China.

Believe it, the Chinese leadership is watching what Trump is doing with the Iranians very closely, as the same thing could happen to them.  They would much rather deal with Trump than engage in an economic cold war with him.

For perspective, note that the top three world economic powers are the US (whose economy is almost twice the size of the Red Chinese economy, even if you accept that their official statistics are correct), the EU, and then China.

The US and the EU have a much closer relationship economically, culturally and historically than they do with the Chinese.  It would be easier, though not easy, for Trump to force the Euros into a trade embargo with the Chinese if the circumstances were correct, than for the Chinese to resist such an effort.  

Prediction: Trump will defeat the mullahs with this strategy within a year or so, and will successfully negotiate a far better economic deal with the Communist Chinese in the same time period.   Double win for us.