二、An unmanned scientific exploration balloon MD-80 owned by the National Scientific Research Institute of Country A entered the Air Defense Identification Zone (ADIZ) and the territorial airspace of Country B. After learning about it, Country B shot down the MD-80 with missiles, but the falling MD-80 smashed the houses and caused three deaths of Country B nationals. Country A asserted that the voyage of the scientific exploration balloon was solely for the purpose of scientific research, but Country B considered that the balloon had illegally intruded into the space under its jurisdiction. Please analyze this incident according to the rules of international law involved. (25 points)