Here’s a lovely piece of history with a huge question mark after it. Since I served under the Erawan in a round about way via USAID and Air America, I find it extremely interesting from several points of view. Obviously, this was well-thought out. As the commenter below the video theorizes, this was not trucked in. The weight alone precludes that. That someone would go to the great lengths they did to recognize and commemorate our service in the adjacent countries of Cambodia and Laos also speaks volumes to their devotion. 

Yes. For all those eagle eyes, that’s a 60mm mortar on top.