Instead of being built like a normal snake with a head at one end and a tail at the other, each segment of this snakebot is totally self-contained with a brain, sensors, motors, and batteries. While the segments are designed to work together to form a long, stealthy snake that can do things like stand up and climb trees, each segment is capable of operating by itself if the snake gets damaged.
The segments can also be configured with alternate payloads, which are separated from the rest of the snake to perform their own missions. So, if the snakebot needs to plant a listening device, it can just disconnect a little piece of itself and leave it behind to eavesdrop. It can also detach segments packed with explosives if it's feeling ornery.
Freakin' snakebots. You know the only thing more frightening than a snakebot? A spiderbot. Which, that reminds me of a joke: What has eight legs, is cold as ice and is climbing your leg right now to bite your nards off? Your girlfriend. Zing!