The wars in Iraq and Afghanistan, which opened the 21st century, are over. The world is seeing new wars, using the latest technologies and new tactics. The Nagorno-Karabakh War in 2020 gave a glimpse of a coordinated campaign using drones, loitering munitions, and new battle command systems. And, as the world watches Ukraine with intense interest, militaries are feverishly trying to learn new lessons. Simultaneously, they are developing the next generation of war-winning weapons. This special publication examines warfare in the 21st century and what game-changing weapons are coming.