Kim Jong Un's private plane flew to Russia, flight data show

July 9 (UPI) -- A private North Korean plane belonging to Kim Jong Un was seen flying to Vladivostok, Russia, and back, according to data from Flight Radar 24.

North Korean Air Force One, also known as Chammae-1, is a modified Soviet jetliner Ilyushin II-62M aircraft.

The plane was captured on radar on Monday making the trip to the Russian Far East and returning to North Korea the same day after three hours, South Korean news agency Yonhap reported.

There is speculation in Seoul the plane was carrying a North Korean working group to Vladivostok ahead of the Eastern Economic Forum to be held in September, according to the report.

Russia has invited Kim to attend the forum, where President Vladimir Putin, as well as Japan's Shinzo Abe and South Korea's Moon Jae-in would be in attendance.

The North Korean leader has yet to respond to the invitation, but last month Kim sent a Korean Workers' Party delegation to the Russian Far East, possibly in anticipation of closer ties with Moscow.

EDaily reported Monday North Korea's national carrier Air Koryo operates regular flights between Pyongyang and Vladivostok, and the charter plane was a "special flight" that drew the attention of monitors.

North Korea's recent round of negotiations with the United States ended with harsh words from Pyongyang regarding U.S. demands for denuclearization, and it is likely Kim is looking toward allies like Russia for support.

North Korea's ongoing engagement with the outside world is taking place following a year when trade was hit by sanctions.

Seoul's Korea Trade-Investment Agency stated Monday that in 2017 North Korea's overall trade fell 15 percent, and Pyongyang's trade deficit reached $2.01 billion, up 125.5 percent from the previous year.

China and Russia are Pyongyang's biggest trading partners.