In mid-September 1939, the ship searched several German merchantmen in Padang, before proceeding to Surabaya for a refit. Throughout 1940, the ship undertook patrol and escort duties as part of the Netherlands East Indies Squadron before escorting ships of the Java–New York Line in a convoy to the Gilbert Islands in early 1941. A new captain, Commander J.B. de Meester, arrived in July. In the final months of 1941, tensions in the region began to heighten amidst concerns about war with Japan and in November 1941 "Tromp" was involved in searches of Vichy French merchant vessels operating in the area. In late November and early December 1941, "Tromp" moved to the western Java Sea to help search for , which was missing after encountering the German raider "Kormoran".