The troops of North Korea's crack invasion units are shorter than the average Western tourist.
I know because I have twice hit my head on the roof of one of the infiltration tunnels that have been discovered beneath the stretch of deceptively peaceful land that divides the Korean Peninsula into North and South.
A South Korean marine keeps a constant lookout into the tunnel as it retreats into blackness to the North, observing through a small embrasure in a thick concrete plug blocking the tunnel. On the surface, 73 meters above our heads, is the most heavily fortified piece of real estate on the planet. And they call it the Demilitarized Zone.