Mick Hartley

This Daily NK report suggests that it's more than just the one border guard defecting across the river to China recently: 

North Korean military units near the Chinese border have recently seen a surge in desertions by soldiers, and in some cases, subsequent cross-border escapes, despite recent security screenings in mid-July by the State Security Department to tighten border control. This has led to the belief that the military is struggling to maintain discipline and order among its troops.

“Recently, five soldiers, from the border patrol 25th brigade based in Ryanggang Province, escaped to Changbai in China,” a source privy to North Korean issues told Daily NK on July 29. “They broke into private homes, openly robbed people, and, in some cases, ripped off doors and threatened local residents or beat them."

Chinese public security forces arrived on the scene after receiving reports from people in the area. This resulted in a standoff with the soldiers, and two police officers sustained severe injuries during the clash….

There were also reports of soldiers going AWOL in the middle of July 27 events marking the North Korea’s self-proclaimed "Victory Day in the Great Fatherland Liberation War [Korean War]," which is the date when the Korean War armistice was signed.

“Even though there were a number of sports activities and entertainment events taking place for V-Day, two soldiers from the 12th corps based in Ryanggang Province abandoned their posts,” a source from Ryanggang Province explained.

He added that the soldiers were very small– approximately 47 to 50 kg and 157 cm tall–and therefore likely undernourished, driven to abandon their posts due to hunger. Discontent with the state may have also played a part. Unable to eat proper meals on a daily basis, these young soldiers would have looked forward to a big meal on Victory Day, but received only a meager serving of seven to ten rice cakes, pickled radish, and watery pork broth.

"That would have been enough to pulled the final string," he surmised….

A high-ranking North Korean official who defected to the South posited that the number of actual cases would surely be higher. "This entire development shows that young soldiers on the Sino-North Korean border are completely distancing themselves from the Kim Jong Un regime in terms of loyalty," he concluded.