This tale is a sad example of how uncoordinated Washington’s policy can be

...In theory, there are reasons why non-American banks might like to grab at this chance. European banks are hungry to find high-return business opportunities, given that interest rates are low in the west. Meanwhile, banks such as Deutsche Bank, BNP Paribas, Standard Chartered and HSBC have long histories in Iran — and clients who want to do business there. Last month, for example, Siemens and Rolls-Royce started talks on new energy investments.

But there is a multibillion-dollar catch. Since 2010, the DoJ has fined non-American banks some $15bn for alleged global infractions of sanctions, anti-money laundering and antiterrorism rules. This includes an eye-watering $8.9bn fine levied in 2014 against BNP Paribas over deals with Iran, Cuba and Sudan...

Unsurprisingly, this sorry piece of history leaves European and Asian banks very nervous and they have asked for watertight guarantees that the DoJ will not penalise them if they heed Mr Kerry’s appeal. He has hitherto been unable, or unwilling, to persuade the department to do this...