Europe faces confidence test as borderless ideal fades

Frankfurt

HERE'S the latest in a long line of threats to Europe's economy: the border guard.

Danish officers checking travel documents on the boundary with Germany this week aren't out to stymie trade or hinder tourism - they're under orders from politicians anxious to stem the flow of refugees. Even so, analysts are beginning to worry about what could happen to the already-embattled region when the free movement of people is called into question.

Like the euro, the single currency used by 19 of the European Union's 28 nations, the Schengen Agreement has long been touted by politicians as an irrevocable pillar of a multinational union, allowing unim…