What jungle are you referring to Puerto Rico?
There's a fair few in the US actually. Obviously none of them are in a state of war right now because the US isn't at war, but they do train a number of troops in them.
The US 25th Infantry Division maintains a jungle fighting school in Hawaii.
en.wikipedia.org
In Puerto Rico there's El Yunque.
en.wikipedia.org
In Florida there's the Mangrove Jungles and Okefenokee.
en.wikipedia.org
en.wikipedia.org
There's a fair few others, a big chunk of the Appalachians is basically one big jungle thicket. It's going to vary since the word "Jungle" has a lot of argument about what it means in the first place, some arguing that only tropics count and some saying it's only in India because it's their word. Obviously not how I meant it, I was going with the old definition of dense plant growth, where generally you need a machete to take a walk.