Dressed in camouflage gear, soldiers gave a demonstration of their martial arts abilities after they'd broken apart pieces of wood and stacks of concrete with kicks, punches and headbutts, Channel News Asia reported.
In a separate demonstration, one Indonesian soldier showed off his shooting skills by wearing a blindfold and firing at a balloon that was in between another soldier's legs. Though one of the shots missed, no injuries were reported, according to Reuters.
In another segment, Mattis looked on as the soldiers brought out a bag of snakes with the intention of killing them and drinking their blood. Though most opted for just cutting the snakes' heads off with knives, one fighter chose to bite the serpent apart. According to reports, the act of serving each other snake blood is a sign of brotherhood.
"You could imagine how much training went into each individual there, that they were able to do that," the Washington Examiner reported Mattis telling reporters. "When you watch a force do that, many small things, perfectly, you can imagine that they can also put the bigger things together."
Some of the other demonstrations included a hostage rescue operation that was acted out while the "Mission Impossible" theme song played in the background.
The display by soldiers follows the recent announcement that Mattis is interested in re-establishing ties with Indonesian counterterrorism troops after human rights abuses prompted the US to impose restrictions on their relationship.