Korean Air launched a twice weekly Busan-Guam service on 28 October.
It uses Boeing 737-800 aircraft on the route, says the carrier.
The SkyTeam alliance carrier also plans to raise the capacity of its Seoul Incheon-Yangon service from 15 November, by replacing the 737-800 aircraft used on the route with Airbus A330-300 aircraft.
It will subsequently increase the frequency of the service from four times weekly to daily on 21 December.
Innovata Schedules show Korean Air as the only operator on the Busan-Guam and Seoul Incheon-Yangon routes.
Korean Air has also confirmed that it will retire its Airbus A300-600 aircraft from service in 2013.
"We are planning to operate our final A300-600 service by early next year and the retired A300s will then be sold at some point. However, the exact time schedule has not been confirmed yet," adds its spokeswoman.
Flightglobal's Ascend Online database show that the airline operates three Airbus A300-600s.