As their rivalry intensifies, U.S. and Chinese military planners are gearing up for a new kind of warfare in which squadrons of air and sea drones equipped with artificial intelligence work together like a swarm of bees to overwhelm an enemy.

The planners envision a scenario in which hundreds, even thousands of the machines engage in coordinated battle. A single controller might oversee dozens of drones. Some would scout, others attack. Some would be able to pivot to new objectives in the middle of a mission based on prior programming rather than a direct order.

The world’s only AI superpowers are engaged in an arms race for swarming drones that is reminiscent of the Cold War, except drone technology will be far more difficult to contain than nuclear weapons. Because software drives the drones’ swarming abilities, it could be relatively easy and cheap for rogue nations and militants to acquire their own fleets of killer robots.