Secret US Military Rocket Balls

The Pentagon has a new secret weapon to neutralize sites containing chemical or biological weapons: rocket balls. These are hollow spheres, made of rubberized rocket fuel; when ignited, they propel themselves around at random at high speed, bouncing off the walls and breaking through doors, turning the entire building into an inferno. The makers call them "kinetic fireball incendiaries." The Pentagon doesn't want to talk about them, but published documents show that the fireballs have undergone tests on underground bunkers.

http://blog.wired.com/defense/2008/11/secret-rocket-b.html