The Korea Customs Service (KCS) intercepted 5.6 kilograms of illicit drugs in 10 separate cases involving international mail from April to July through a newly established secondary screening network, the agency said Thursday. In particular, it used controlled deliveries, a covert investigative technique, to track the shipments, resulting in the arrest of all suspects involved. The new method involves a dual-layer drug screening system established in cooperation with Korea Post in April. Under the system, international mail that passes initial inspections at the border is subject to additional screening at one of five major postal distribution centers nationwide. Central to the agency’s success in arresting all suspects was the strategic use of controlled deliveries, under which law enforcement officers deliberately allow intercepted parcels to proceed to their destinations while remaining under tight surveillance. Because international mail allows authorities to maintain the normal delivery process without alerting traffickers, the tactic enables investigators to identify actual recip