(NewsNation) — U.S. Army troops are conducting jungle training in Hawaii, preparing for possible warfare in the Indo-Pacific region in what is a clear signal of China’s increased aggression.

Deep in the jungles of Oahu, soldiers are confronted with mock ambushes as part of a two-week training program. The terrain of the jungle is similar to what is found in the Philippines or Taiwan.

The difficult conditions of the terrain and the intense training mean not everyone is able to complete the program. The latest class started with 93 soldiers and is now down to 53.

“With all of your packing list inside the ruck, the ruck is pretty heavy, and then moving from Blackhawks to the jungle and being quiet is pretty difficult,” said Capt. Sabrina Rooker, an Army jungle training candidate.

“We focus on mobility. So rope-based mobility, waterborne, tracking, survival and land navigation — those are the five skills we want to pass on to students,” company commander Capt. Mac Lalor told NewsNation.

Even for those soldiers who served in Iraq and Afghanistan, the conditions are proving to be brutal.

“The environment is vastly different. Like I said, everything from the terrain to just the critters, you have to worry about jaguars, anacondas, stuff like that, leeches. It’s wet. So in the jungle, if you’re not wet from the rain, from being in the waterway, you’re wet from sweat because it’s so humid,” said Sgt. 1st Class Gerald Squirlock, senior jungle operations instructor.

The ongoing ramp-up in the Pacific also includes additional training between U.S. branches along with more training and exercises with ally countries like Australia, Japan and South Korea.

A few weeks from now, the 25th Infantry will have even more soldiers going through jungle training, this time in the Philippines, where Chinese ships have repeatedly provoked Filipino fishing boats near the disputed Spratly Islands.