at the time of the KAL crash at GUM, Air Nauru was already operating under an Australian AOC. Willing to be corrected, but worth checking to be sure ..............
The Korean Air B747 crash at Guam was in 1997. The Australian CAA granted Air Nauru an AOC in 1998. In fact, it was the NZ CAA who canned the bi-lateral agreement between Nauru and New Zealand which started the rot. A NZ audit of Air Nauru revealed a serious lack of a proper regulatory oversight of the airline by the Nauruan DCA. And they were dead right.
NZ then stopped Air Nauru carrying passengers to NZ. Following the New Zealand move, the FAA then down classified Air Nauru to a level 2 operator or similar low level grade. This prevented the airline from operating into US FAA airports such as Guam. As Nauru traditionally had closer ties with Australia than New Zealand particularly in relation to aviation matters, the obvious way out was to apply for an Australian AOC and have VH registration. It was a good move.