The European Union will for the first time enforce its “Blocking Statute” to protect firms doing business with Iran from the sanctions the US is re-imposing on Tuesday and tightening in November with a ban on oil sales. France, Germany, Russia and China stayed in the 2015 nuclear deal with Iran after the US quit in May. The Blocking Statute may be difficult to enforce. It first needs updating as well as the consent of all 28 EU member states. Since this could take time, some major European firms have taken the precaution of breaking off business ties with Tehran to avoid becoming targets of US sanctions and losing the American market.