South and North Korea should pour continued efforts into national unification without being swayed by changes in cross-border relations, Seoul's unification minister said Monday. Amid recent signs of thawing inter-Korean relations, South Korea has revved up efforts to stress the need to achieve reunification of the peninsula, with President Park Geun-hye calling it a "bonanza." The Koreas remain technically at war, as the 1950-53 Korean War ended in an armistice, not a peace treaty. "We need to strive to improve the inter-Korean relations, but it is wrong if it causes our discussions for the reunification to be neglected," Unification Minister Ryoo Kihl-jae said during a meeting of the Central Association for National Unification of Korea in Seoul. "Better inter-Korean ties do not always guarantee national reunification ... and for decades, we've paid little attention to the crucial and comprehensive issue of unification," he pointed out, stressing it should be "a main, regular issue on the table."    Calling a process for the reunification "a project to complete the nation," he called on the people as well as the international community to join hands for the efforts. "South Korea successfully achieved the project of developing the country decades ago. Now is time to push for the reunification project to perfect the nation," Ryoo said. He then stressed three key principles in getting prepared for the reunification -- making a vision in a creative way, taking a rational, cool-headed stance, and seeking unity of the society. "Reunification of the Korean Peninsula is not a matter of choice but a must that will give people hope and opportunities."