Russia's state-run Sputnik International news organization reports there are indications North Korean leader Kim Jong-un may be about to visit Russia.

Sputnik says three Air Koryo cargo aircraft are scheduled to depart Pyongyang for Vladivostok on Sunday, noting the flight schedule is not part of the regular passenger flight operations between the two countries.

A Web site run by Vladisvostok International Airport says three planes are expected from Pyongyang to land at 9 a.m., 11:10 a.m., and 5 p.m. on Sunday.

Sweden-based aircraft tracker Flightradar 24 says the same aircraft were used for the North Korean leader's earlier visits to Beijing and Singapore.