I read this short story a while ago. It described a futuristic war fought by robots.
It featured a team of some sort of military elite going in an underground train (which broke on the way) to their central underground operations command center, which they used to control robots out on the battlefield. There, they find the last living operator in poor condition because the enemy sent in some sort of worm-like burrowing drones that unleashed a heat attack on the base. The new arrivals try to deal with the threat, but are eventually forced to leave. They consult their headquarters and leave behind a robot to take control over all of operations, since it could not be weakened by a heat attack, and the walls of the command center could still resist any damage. Then the officers make their way outside to the chaotic surface, where they are greeted by some strange people who claim to be the commanding officers of the enemy army. They also left the control of their operations to a robot, and now the war essentially turned into a purposeless all-out battle of constantly evolving robots, where any humans have little chance of survival.
Can someone help me find the name and the author of this story? I think it might have been written by Harry Harrison.