Donald Trump Jr. had a Mongolian wildlife adventure, and it landed him with something much more controversial than a horse he couldn't bring home.

Trump Jr. visited the Asian country in August along with his son, using a government-funded security service and even meeting with Mongolia's President Khaltmaagiin Battulga while he was there. And at some point along the way, Trump Jr. shot and killed an argali — an endangered giant sheep that's considered a "national treasure" in Mongolia, ProPublica reports.

Argali are the world's largest breed of sheep, and carry around a massive set of curving horns that make them susceptible to hunting. That's why in Mongolia, people need a permit to hunt them, and that "opaque permitting system ... is mostly based on money, connections and politics," ProPublica has learned from experts. Trump Jr. seemingly fit the bill and ended up with one of those licenses — though not until he'd already left the area and killed an argali. The permits are rare enough, with only three being issued in the region Trump Jr. was visiting. And it's even rarer for them to be issued retroactively, ProPublica says.

A spokesperson for Trump Jr. said he'd purchased the Mongolian hunting trip at a National Rifle Association charity auction before his father announced his presidential candidacy. It wasn't clear if that included the presidential meeting or specifically killing this rare sheep. Read more at ProPublica. Kathryn Krawczyk