North Korean leader Kim Jong-un lays a wreath at the Liberation Tower in Pyongyang on the occasion of the 81th anniversary of Liberation Day, in this photo released by the North's official Korean Central News Agency on Saturday. (Yonhap) 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 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 since the two countries forged a comprehensive strategic partnership in 2024, which laid the groundwork for North Korea's military support for Russia in its war against Ukraine.Kim was accompanied by his daughter, Ju-ae, and his wife, Ri Sol-ju. It marked Ju-ae's first known appearance accompanying her father on a visit to the tower.On Saturday, Russian President Vladimir Putin sent a congratulatory message saying the two countries were actively cooperating across sectors and making concerted efforts to ensure regional security and stability, according to the KCNA.Putin said their "militant friendship and mutual assistance" had elevated bilateral ties to an "unprecedentedly high level of comprehensive strategic partnership.""I am convinced that we would as ever conduct constructive joint undertakings on the pressing bilateral and international issues," Putin was quoted as saying, apparently referring to growing military cooperation, including North Korea's troop deployment to support Russia's war in Ukraine.Former Russian President Dmitry Medvedev also sent greetings to Kim, the KCNA said.The messages and Kim's visit underscore deepening ties between Moscow and Pyongyang, particularly their expanding military cooperation, which has drawn international concern over North Korea's support for Russia's war in Ukraine.