North Korea is believed to be continuing military drills mobilizing fighter jets, air-cushion vehicles and submarines as usual despite global sanctions prohibiting the regime's access to aircraft fuel. 

A South Korean government source said that such drills are taking place at the same level as past years. 

North Korea typically declares the time from June 25th, which marks the start of the Korean War, to July 27th, when the war armistice was signed, as a period of struggle against the United States, and holds summer drills through August.

The source said the North appears to be using its oil reserves as training of combat planes continues, or that there could be a channel continuously supplying the North with fuel for military use.

The source added that the move could also be a type of psychological warfare to demonstrate that Pyongyang is unaffected by sanctions.