One by one, the American soldiers slid down a muddy hillside to a river deep in the Hawaiian jungle. With guns on top of rucksacks, they kicked their way across, wobbling in the current, trying to stay quiet.

It was a sluggish advance stinking of sweat and silt ¡ª reminiscent of Vietnam and similar to what they might face in a potential fight with China almost anywhere in the Pacific.

¡°It¡¯s incumbent on us to become resident professionals,¡± said Col. Christopher Johnson, who traversed the river arm in arm with a junior officer. ¡°Firemen don¡¯t figure out how to work a fire engine at the fire, right?¡±