and on October 9 conducted its first nuclear test. A second inter-Korean summit was held in 2007. By 2017, estimates of North Korea's nuclear arsenal ranged between 15 and 60 bombs, probably including hydrogen bombs. In the opinion of analysts, the Hwasong-15 missile is capable of striking anywhere in the United States. There was an increase in militaristic rhetoric on both sides. Thaw at the Winter Games In May 2017 Moon Jae-in was elected President of South Korea with a promise to return to the Sunshine Policy. In his New Year address for 2018, North Korean leader, Chairman of the Workers' Party of Korea Kim Jong-un proposed sending a delegation to the upcoming Winter Olympics in South Korea. The Seoul–Pyongyang hotline was reopened after almost two years. At the Winter Olympics, North and South Korea marched together in the opening ceremony and fielded a united women's ice hockey team. As well as the athletes, North Korea sent an unprecedented high-level delegation, headed by Kim Yo-jong, sister of Kim Jong-un, and President Kim Yong-nam, and including performers like the Samjiyon Orchestra. The delegation passed on an invitation to President Moon to visit North Korea. An opinion poll taken on 15 February found that 61.5% of South Koreans thought Moon should take up the invitation. The performances by the Samjiyon Orchestra at the Olympics marked the first time since 2006 that any North Korean artist performed in South Korea. The North Korean ship which carried the orchestra, Man Gyong Bong 92, was also the first North Korean ship to arrive in South Korea since 2002. Following the Olympics, the governments of North and South Korea raised the possibility that they could host the 2021 Asian Winter Games together. On 1 April, South Korean K-pop stars performed a concert in Pyongyang titled "Spring is Coming", which was attended by Kim Jong-un and his wife. Meanwhile, propaganda broadcasts stopped on both sides. The K-pop stars were part of a 160-member South Korean art troupe which performed in North Korea in early April 2018. It also marked the first time since 2005 that any South Korean artist performed in North Korea. April 2018 inter-Korean summit On 27 April, a summit took place between Moon and Kim in the South Korean zone of the Joint Security Area. It was the first time since the Korean War that a North Korean leader had entered South Korean territory.