I know, this question probably have asked many times, but I unable to post in that closed threads, so... We have a Planet, (let's say of size of the Earth, and that have a population of the Intelligent Creature - IC, on level of evolution and progress something near a mankind current level, so wee need to take into account the defensive possibilities of the particular population of IC, such as a very deep placed underground shelters, etc), We have a small Space Fleet (it is not the armada but it is not a recon squadron too). And in some crazy reason we have order to destroy this particular Planet in the worst case, or to exterminate the any existing life forms on this planet, this is including bacteria, etc. What kind of weapon we better need to use to "sterilize" this Planet? Biological Microrobots (Nano-organic stuff) Radiation Kinetic weapon / Climate (I mean use disruption in this planet surface to provoke ground shakes, volcano, water fluids etc) A combination Other variants What kind of weapon we better need to use to destroy (shred to the small pieces and split over the Star-System) this Planet? Matter/Antimatter Somekind of Gravity weapon (like a Black Hole) Ray/Beam like stuff Kinetic (Meteor/Neutron Star like) A combination Other variants What a more likely defensive measures of the Planet' IC population will be in the first case Consolidation, uniting into a single allience Separating, and trying to negotiation Attack by Nuclear Weapon, Matter/Antimatter, etc Trying to escaping to another nearest Planet that have suitable conditions A combination Other variants Thanx for the answers :) .