Several North Korean oil tankers reappeared on international tracking systems in recent weeks the NK Pro vessel tracker shows, after a long hiatus that saw their activity reduce dramatically.

While the DPRK’s tankers were a common sight at several Chinese and Russian ports in the first quarter of the year, many of them seemed shelved as U.S. targeted Russian oil companies and reports circulated that China had suspended fuel deliveries.

But four tankers recently reappeared on international tracking systems, though without broadcasting their destinations.

Most recently, a North Korean crude oil