Last week, China seized a U.S. Navy drone. The capture signaled Beijing’s displeasure with U.S. reconnaissance in the South China Sea, but avoided endangering U.S. personnel and giving Washington a reason to escalate.

Get used to this. Attacks on remotely controlled vehicles — drones — may become a new currency for coercive diplomacy, enabling nations to challenge rivals without hurting an opponent’s military personnel — and so without risking significant escalation.