The Japanese government on Friday published images showing what appears to be a North Korean oil tanker engaged in sanctioned activity with a vessel of unknown nationality on the high seas in May.

The images – taken on May 24 by the Japan Maritime Self-Defense Force – show the already-sanctioned Sam Jong 2 alongside another vessel, suggesting a Ship-to-Ship (STS) transfer, which is prohibited under current UN Security Council (UNSC) resolutions, had taken place.

“In the daytime on May 24, 2018, a JS ‘UMIGIRI’ (Escort Division12: Kure) of Japan Maritime Self-Defense Force found that SAM JONG 2 (IMO number: 7408873),