Modern war is decided by technology, not toughness.
The Iraqis was battle hardened after decades of Iran-Iraq war. Once the good USA came, it only took weeks for Iraq to tumble.
The Chines prior to WWII were a battle hardened outfit after decades of civil wars during the warlord period. The Japanese were able to defeat them.
Today's war is about equipment, intelligence, training, latest tech. It is not depend on how tough your army is.