North Korea’s Ilyushin Il-76 cargo planes have made multiple trips to the northeast coast in the last month, according to NK Pro analysis of satellite imagery, a rare occurrence pointing to urgent shipments, possibly of military-related items.

Work to convert one of the DPRK’s three Il-76s into a military detection and warning aircraft also resumed one month ago, Planet Labs imagery shows.

The activity comes as national carrier Air Koryo has resumed normal operations this year with flights from Pyongyang to China’s Beijing and Shenyang and Russia’s Vladivostok, after grounding