By Josh Smith and David Brunnstrom SEOUL (Reuters) -North Korea fired a short-range ballistic missile into the sea off its east coast on Friday, South Korea’s military said, the latest in a series of launches by the nuclear-armed country. Earlier, South Korea’s military said it scrambled fighter jets when a group of about 10 North Korean military aircraft flew close to the border dividing the two countries, amid heightened tensions over repeated North Korean missiles tests. North Korea’s official KCNA news agency quoted the North Korean military as saying it took “strong military countermeasur…