North Korean leader Kim Jong-un has paid tribute to Soviet soldiers who fought against Japan during World War II to mark Korea's liberation from Japanese colonial rule, vowing to further strengthen ties with Russia, Pyongyang's state media reported Saturday. Kim visited the Liberation Tower in Pyongyang on Friday, a day before the 81st anniversary of Korea's liberation from Japan's 1910-45 colonial rule, the North's Korean Central News Agency (KCNA) said. Kim laid a wreath bearing the phrase, "We will not forget the feats of the martyrs of the Soviet Army." "The excellent history, traditions and ties of blood between the DPRK and Russia now serve as a fundamental cornerstone and inexhaustible driving force for the bilateral relations of friendship and cooperation," Kim said in an English dispatch. He added that their "great friendship and unity" would be carried forward "generation after generation." DPRK is the acronym of North Korea's official name, the Democratic People's Republic of Korea. It marked the third time Kim has visited the Liberation Tower on the occasion of Liberation Day s