Seoul, Sep 18 : North Korean leader Kim Jong Un has left the Far Eastern city of Vladivostok for home after "successfully" completing a visit to Russia that will open up a "new chapter" in their bilateral relations, Pyongyang's state media reported on Monday. During the six-day trip, Kim held a summit with Russian President Vladimir Putin on Wednesday and toured a series of key military sites amid growing concern about possible military cooperation between the two countries. "Kim Jong Un, general secretary of the Workers' Party of Korea and president of the State Affairs of the Democratic People's Republic of Korea, left Vladivostok City on September 17 after successfully completing the schedule of his official goodwill visit to the Russian Federation," the North's official Korean Central News Agency (KCNA) said. During his stay, Kim pledged to throw his full support behind Putin, saying the Russian army and people will triumph over "evil" forces, in an apparent endorsement of Russia's war in Ukraine. Kim also went on a tour of Russia's Far East, visited key military facilities in the region and held talks with Russian Defense Minister Sergei Shoigu in Vladivostok to discuss strengthening bilateral military cooperation and exchanges. The makeup of his entourage and the selection of Russia's space facility as the venue for talks spawned speculation that North Korea may agree to supply Russia with ammunition and weaponry in exchange for food aid and a transfer of weapons technology from Moscow, such as those involving spy satellites and nuclear-powered submarines. The KCNA said Kim's visit will be marked as "further consolidating the traditional ties of good neighbour and cooperation" between the two countries "based on the comradely friendship and militant unity and opening up a new chapter of the development of the bilateral relations." This was the longest overseas trip by Kim since taking power. Including travel time, the North Korean leader spent a total of eight days on his visit to Russia. South Korea has warned against possible military cooperation between North Korea and Russia, with the presidential National Security Council warning that the countries will "clearly pay the price" should they engage in actions violating the United Nations Security Council resolutions. Seoul's unification ministry spokesperson, Koo Byoung-sam, reiterated the stance in a press briefing Monday and said the government will "closely monitor" signs of possible cooperation between Pyongyang and Moscow. /IANS