It was hostile and illegal activity by the US directed against the EU itself. The EU has neither the capacity nor the authority to conduct any reciprocal surveillance of US missions in Europe, and it does not do so.
但被指控的事件并非美国针对他国非法行为的以牙还牙，而是美国针对欧洲本身的非法敌对行为。欧盟既没有能力、也没有权力针锋相对地监视美国驻欧洲使团，也没有这样做。海登对此心知肚明。