Japan put its ballistic missile defences on alert on Monday and vowed to shoot down any projectile that threatens its territory, after North Korea notified it of a planned satellite launch between May 31 and June 11. The nuclear-armed North says it has completed its first military spy satellite and leader Kim Jong-un has approved final preparations for the launch. Tokyo expects North Korea to fire the rocket carrying its satellite over Japan’s southwest island chain, a defence spokesman said. Japan would use its Standard Missile-3 or Patriot Missile PAC-3, he added.