One of North Korea’s only undesignated oil tankers returned to the Russian Far East earlier in November and took up position near an oil terminal owned by a U.S.-sanctioned company, the NK Pro ship tracker showed this week.

The visit is the 949-tonne Ma Du San’s second trip to the area in the space of a month, though it was also briefly detained on safety grounds when it arrived in Russia last month.

Much like in the first visit, the North Korean tanker headed to waters near an oil facility which