Complex sentence: By result of this event, ROK government canceled its Military Reform Plan 2020 which was to downsizing scale of Marine Corps in North-West islands and established Military Reform Plan 307 (Plan 307).
Split into simpler sentences: By result of this event, ROK government canceled its Military Reform Plan 2020 which was to downsizing scale of Marine Corps in North-West islands. Instead, established Military Reform Plan 307 (Plan 307).