To counter the carrying of high-value contraband goods to and from the Americas, the BSC set up a network of observers on merchant ships. The agents, recruited from the crews (and among pro-British masters) of the vessels, would report their observations, cargo manifests, and passenger lists to agents in port when they arrived. Agents watching docks at both ends also gathered intelligence. Ships or enemy agents could be intercepted and US and British lines could blacklist questionable crew from employment. From autumn 1941, the BSC handed over control of observers on American vessels and ports to the US while retaining control of the remainder and maintaining close liaison with the new US handlers.