As American officials sound the alarm over what they call a resurgent threat from the Shiite militant group Hezbollah, thousands of its members and supporters operate with few restrictions in Europe, raising money that is funneled to the group’s leadership in Lebanon.

Washington and Jerusalem insist that Hezbollah is an Iranian-backed terrorist organization with bloody hands, and that it is working closely with Tehran to train, arm and finance the Syrian military’s lethal repression of the uprising there. Yet, the European Union continues to treat it foremost as a Lebanese political and social movement.