Russia published a video of a D-74 artillery system last week, a gun that Moscow is thought to have received from North Korea.Russian Defense MinistryRussia filmed its troops firing a D-74, an artillery gun developed in the 1940s that the Soviets exported to their allies.Its appearance is giving rise to suspicions it was brought back in from countries like North Korea.Military experts say that even if it wasn't imported, its age shows a growing strain on Russian stockpiles.Last week, a promotional video from the Kremlin caught the attention of Ukrainian media covering the war.The clip showed an entrenched Russian crew firing an old, towed artillery system against Ukrainian positions in Donetsk.The field gun featured: a D-74 122mm howitzer, which the Soviet Union developed in the late 1940s.Yet its age wasn't the main attraction.