Story highlights This would be Kim Jong Un's first official foreign trip as North Korea's leader

The Soviet Union and North Korea enjoyed strong ties in the past

Moscow (CNN) Kim Jong Un is expected to attend World War II anniversary celebrations in Moscow at Russia's invitation, a Russian official speaking on condition of anonymity said Thursday.

North Korea accepted Russia's invitation, but Russia is waiting on Pyongyang to make the official announcement about the May trip, the official said. This would mark Kim's first official foreign trip since inheriting the leadership in late 2011.

"The invitation was sent to Kim Jong Un. North Korea accepted the invitation. The leadership of North Korea is expected to take part in Victory Day celebrations in Moscow," the Russian official said.

The official later clarified: "By leadership, we're talking about Kim."

Photos: North Korea's friendships Photos: North Korea's friendships North Korea and Russia declared 2015, which is the 70th anniversary of the end of World War II, as "Friendship Year." The two countries have intensified their relationship, with goals to increase trading to $1 billion a year. Hide Caption 1 of 7 Photos: North Korea's friendships Cozy relations between North Korea and Russia aren't exactly new. After all, the Kim regime has long had ties to Russia. This photo from August 29, 2011 by North Korea's official Korean Central News Agency shows Russia's now Prime Minister Dmitry Medvedev shaking hands with the late North Korean leader Kim Jong Il. Hide Caption 2 of 7 Photos: North Korea's friendships North Korea's Foreign Minister Ri Su Yong is on an international trip this month spanning Belarus, Russia and Cuba. In Havana, Ri met with Cuba's Foreign Minister Bruno Rodriguez. The two Communist countries have maintained ties since 1960s. Cuban media reported that its president Raul Castro also received Ri. Hide Caption 3 of 7 Photos: North Korea's friendships North Korean Foreign Minister Ri Su Yong stopped in Belarus last week. At a meeting in Minsk, Belarus and North Korean officials discussed the UN and the principles of non-interference, according to North Korean state media, KCNA. Ri is seen with Belarus Foreign Minister Vladimir Makei on March 9, 2015. Hide Caption 4 of 7 Photos: North Korea's friendships Rarely a week goes by where the North Korean state media doesn't trumpet its friendship with Syria's president Bashar al-Assad. A North Korean delegation visited him in Syria on March 8, according to KCNA. North Korea officials hailed Syria's standoff with the U.S. saying: "The hostile acts of the U.S. imperialists make the relations between Syria and the DPRK stronger." Hide Caption 5 of 7 Photos: North Korea's friendships Iran and North Korea have enjoyed a long-term partnership, raising concerns for the U.S. about advancing their nuclear and missiles program. Iranian President Hassan Rouhani met with North Korean officials in Tehran on September 16, 2014. Hide Caption 6 of 7 Photos: North Korea's friendships North Korea's mass games, the annual spectacle, regularly features the flags of both North Korea and China. The two countries have been longtime historic allies since China came to the aid of North Koreans during the Korean War. However, some observers believe relations between the two nations have cooled recently. Hide Caption 7 of 7

So far, North Korean state media has not issued any statement about the invitation.

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