Various Russian carriers in the last few days closed reservation for service to Korea, with the exception of Moscow. Currently most flights are closed for booking during the month of March 2020, including following routes.
Aeroflot operated by Aurora
Khabarovsk – Seoul Incheon 01MAR20 – 28MAR20 1 daily closed for reservation
Vladivostok – Busan 01MAR20 – 28MAR20 7 weekly closed for reservation
Vladivostok – Seoul Incheon 01MAR20 – 28MAR20 2 daily closed for reservation
Yuzhno-Sakhalinsk – Seoul Incheon 01MAR20 – 28MAR20 4 weekly closed for reservation
S7 Airlines
Irkutsk – Seoul Incheon 01MAR20 – 28MAR20 3 weekly closed for reservation
Novosibirsk – Seoul Incheon 01MAR20 – 28MAR20 4 weekly closed for reservation
Vladivostok – Seoul Incheon 01MAR20 – 28MAR20 12 weekly closed for reservation
Yakutia
Yakutsk – Seoul Incheon 01MAR20 – 28MAR20 2 weekly closed for reservation (Reservation is also closed for summer season from 29MAR20 for the moment)