The 10 years' application of the Sunshine Policy was not reciprocated by North Korea and proved to have failed to change North Korea as clearly demonstrated by the torpedo attack against the South Korean Navy corvette, the Cheonam, on the 26th of March 2010. North Korean leaders did not give up their aggressive policy toward South Korea and do not show any sincerity on dialogues with South Korea. They still continue to develop nuclear weapons to threaten South Korea and the US The Sunshine Policy did not work on North Korea and only reinforced that the relationship between South Korea and North Korea is still zero-sum. North Korea needs to be understood and dealt with as the rival in a zero-sum game, for example, the Chicken Game, with South Korea. Different from the leaders of the former two administrations, the current South Korean President, Lee Myung-bak, came to realize the unchanged zero-sum nature of South-North relations. He demanded that North Korea demonstrate its sincerity for the welfare of its people in return for the assistance and dismantle its nuclear weapons program. The US President, Barack Obama, also quickly realized the true nature of North Korea and joined in President Lee's policy. As a result, a glimpse of hope started to be seen until the attack on the Cheonan warship. In order to change North Korea, democratic nations including South Korea and the US should keep cool-headed before warm-hearted and continuously compel North Korea to change. They should be united and tough in punishing North Korea's provocations. The warm-hearted engagement efforts for the North Korean people should be complementary. South Korea and the US should accurately assess the situation with facts and be consistent and resolute in the implementation of their policies. If democratic nations succeed to keep consistent pressure, North Korea would change its patterns of behavior, like a child who recognized the clear red lines of the parents. It will be very difficult to maintain the principled policies consistently and keep the pressure on North Korea, because public opinion, domestic and international, would press the governments of South Korea and the US to care more about the humanitarian needs and be generous to the North Korean regime. A small changed gesture of North Korean leaders would induce the leaders of democratic nations to loosen the pressure, which has been the case in the past. Without resolute consistent pressure until the real change of North Korea, most policies would end up enjoying only a short-lived success.