A shock visit by one of North Korean leader Kim Jong-un's closest aides to South Korea is "unprecedented" and has opened up high-level communication between the two rivals that has been missing for years, according to analysts. Whether it is a line of communication that will endure or produce lasting results remains to be seen, but Saturday's visit by a trio of top-ranking officials provided an opportunity that few saw coming. "It's huge," said Andrei Lankov, a professor of Korean studies at Kookmin University in Seoul. "Apart from anything else, the level was pretty much unprecedented in terms of previous delegations to the South," Lankov said. "Essentially it provided a direct line to Kim Jong-un." It was led by Hwang Pyong-so, a newly elected vice-chairman of the nuclear-armed North's powerful National Defence Commission, who is widely seen as Kim Jong-un's number two. Accompanying him was another Kim confidant Choe Ryong-hae and Kim Yang-gon, a top ruling party secretary with responsibility for South Korean affairs. The sudden visit was all the more surprising for coming after months of military tensions and vicious personal attacks in the North's state media against South Korean President Park Geun-hye. Seoul was only informed on Friday of the trip, which was ostensibly made to coincide with the closing ceremony of the Asian Games in Incheon. "This was clearly no pro-forma visit. It was a very big deal indeed," said John Delury, a North Korea expert at Yonsei University in Seoul. "If you are Park Geun-hye and you want a credible channel to the leadership in Pyongyang, then this is your dream team," Delury said. One immediate impact was an agreement to resume a high-level dialogue that has been in limbo for seven months. The last round in February resulted in the North hosting a rare reunion for families separated by the 1950-53 Korean war.