When U.S. and Australian troops practiced amphibious landings, ground combat and air operations last summer, they drew headlines about the allies deepening defense cooperation to counter China's growing military ambitions.

But for U.S. war planners preparing for a potential conflict over Taiwan, the high-profile Talisman Sabre exercises had a far more discreet value: They helped create new stockpiles of military equipment that were left behind in Australia after the drills ended in August, U.S. officials said.

The United States and its allies are increasingly worried that in the coming years, Chinese President Xi Jinping could order his military to seize Taiwan, the democratically governed island China considers its own territory. So, the U.S. military is taking a hard look at its own military readiness and trying to play catch-up in a critical area: its logistics network.