Lone wolf jihadis operating in Europe are following a doctrine of 19th century warfare in which they are given a deadline and a target - then sent to attack it by any means necessary. Invoking the Germany Army's historical strategy of Auftragstaktik, the policy helps ISIS carry out attacks abroad when its chain of command is restricted by Western intelligence agencies. This allows operatives hiding in Europe to inflict terror with a large degree of autonomy, while also inhibiting authorities from tracing their chain of command.