For most armed forces, the ammunition that they require will vary in size from 0.22-caliber bullets to GPS-guided missiles and contain explosive charges somewhere in the design. It is essential that ammunition is kept dry if explosive propellants, and charges are to function effectively. Ammonium nitrate, gunpowder, solid fuel, etc. are extremely sensitive to moisture and will become completely ineffective if stored in uncontrolled conditions. Ammonium nitrate naturally becomes explosive in high humidity conditions. The correct storage of ammunition is a vital security consideration in defense operations.