Chapter 5 uncovers networks used to control flows of communist ideology, activists, and weapons from port cities across Asia to the Netherlands East Indies. The Dutch Consulate in Shanghai worked together with British and French intelligence agencies to track movements of known or suspected Indonesian communists across transoceanic networks linking Russia, China, and the Netherlands East Indies. The Java-China-Japan Lijn played a role in these policing efforts, as maritime workers were specifically targeted for their anticolonial affiliations, and the company was asked by colonial administrators to patrol ships for subversive people, anticolonial propaganda, and smuggled armaments. Communist supporters routinely subverted these controls and were able to build networks connecting the Partai Komunis Indonesia with the Comintern and other organizations around the globe. For example, outrage over a sexual assault onboard JCJL’s MS Tjibadak in 1930 sparked an anti-Dutch boycott in Chinese port cities ‒ catalyzed by Chinese diasporas linking East and Southeast Asia ‒ and provoked a transnational dialogue and critique of Dutch imperialism in Asia.