Well ... truth be told the Vietnamese are still investigating and for now it is classified as a 'UFO'
An unidentified flying object exploded in mid-air over a southern Vietnamese island, state media said Wednesday, a day after Cambodia's air force retracted a report of a mysterious plane crash. "The explosion happened at about 8 km (5 miles) above the ground, and perhaps it was a plane, but authorities could not identify whether it was a civil or military aircraft," VNA said in a report headlined "UFO explodes over Phu Quoc Island."
Soldiers were sent out to look for wreckage and survivors, and local authorities contacted airlines in Vietnam, Cambodia and Thailand, but received no reports of missing aircraft, the official state news agency added. (Telegraph)