Soldiers from 1st Special Forces Group (Airborne) recover a GD-2000 glider at Yuma Proving Grounds in Arizona in February.US Army/Sgt. Thoman Johnson The US military is preparing for a future where its ability to resupply troops is challenged. The effort reflects expectations that potential foes, mainly China, can attack US supply lines. In February, Special Forces soldiers tested a glider that could deliver supplies without detection. The war in Ukraine has offered the US military a glimpse of how large-scale conventional conflicts will be fought in the 21st century.To be sure, the US military has vastly better capabilities than either the Ukrainian and Russian militaries, but fierce fighting in Ukraine has shown the value of old technology and the limits of new hardware.The war in Ukraine has only accelerated the US military's adjustments to the challenges it expects to face in future wars.