I was a military intel officer stationed in South Korea in the early 1990s. At Panmunjom, each side utilizes MPs who are physically large and intimidating, for psychological reasons. Most of the Americans I saw were 6’2” or taller, and looked like they could play middle line backer in the NFL. Most of the ROK guards were strapping specimens, too. Not quite a large as their U.S. counterparts, but very big by South Korean standards. By comparison, the “monsters” from the DPRK were a good 4-5 inches shorter (or more) than the ROK MPs and at least 40 pounds lighter. The Norks tried to bulk their guys up before sending them to Panmunjom, but you couldn’t overcome years of malnutrition in a matter of months.
Today, the average South Korean is a head taller and 40 pounds heavier than the typical North Korea. It’s also become more difficult for the Norks to train agents to blend in among the South Korean populace. No only is there the “size” factor, they must also deal with a language issue. Thanks to international travel and exposure to other cultures/languages, the South Korean dialect is decidedly different than the standard North Korean dialect.
Starving your people for 50 years (and keeping them in isolation) has real consequences.
Ever hear of Miracle Gro?