Supreme Leader Kim Jong-un of North Korea sent a series of letters to South Korean outgoing President Moon Jae-in with a rare tone of appreciation.

Kim, the totalitarian dictator of North Korea, is not known for his kindness toward the leadership of South Korea. However, in a correspondence with Moon over the course of several weeks, Kim wrote warm words of diplomacy rarely seen between the fractured countries.

"Kim Jong Un appreciated the pains and effort taken by Moon Jae-in for the great cause of the nation until the last days of his term of office," North Korean state media said of the messages, calling them an "expression of their deep trust."

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Moon confirmed the exchange of letters and spoke optimistically about the possibility of a reunified Korea in the future. 

In this photo provided by the North Korean government, North Korean leader Kim Jong Un, center, waves from a balcony toward the assembled troops and spectators during a celebration of the nation’s 73rd anniversary at Kim Il Sung Square in Pyongyang, North Korea, early Thursday, Sept. 9, 2021. Independent journalists were not given access to cover the event depicted in this image distributed by the North Korean government. The content of this image is as provided and cannot be independently verified. Korean language watermark on image as provided by source reads: "KCNA" which is the abbreviation for Korean Central News Agency. (Korean Central News Agency/Korea News Service via AP)

In this photo provided by the North Korean government, North Korean leader Kim Jong Un, center, waves from a balcony toward the assembled troops and spectators during a celebration of the nation’s 73rd anniversary at Kim Il Sung Square in Pyongyang, North Korea, early Thursday, Sept. 9, 2021. Independent journalists were not given access to cover the event depicted in this image distributed by the North Korean government. The content of this image is as provided and cannot be independently verified. Korean language watermark on image as provided by source reads: "KCNA" which is the abbreviation for Korean Central News Agency. (Korean Central News Agency/Korea News Service via AP) (Korean Central News Agency/Korea News Service via AP)\)

Moon has been a continued advocate for greater cooperation with the hermit kingdom, helping facilitate the meeting of Kim and former US President Donald Trump in 2019.

North Korea continues to be a cause for concern to its neighboring countries. Specifically, Japan has expressed disapproval of North Korean missile and weapons testing in areas not far from the island nation.

South Korean President Moon Jae-in speaks during a meeting with his senior secretaries at the presidential Blue House in Seoul, South Korea, Monday, Sept. 28, 2020. (Lee Jin-wook/Yonhap via AP)

South Korean President Moon Jae-in speaks during a meeting with his senior secretaries at the presidential Blue House in Seoul, South Korea, Monday, Sept. 28, 2020. (Lee Jin-wook/Yonhap via AP)

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The Pentagon addressed a report from North Korean state media that the country had tested a "tactical guided weapon" on Sunday, with the stated goal of boosting its nuclear fighting capability.

North Korean leader Kim Jong Un and other top officials reportedly observed the launch. According to state media, the weapon they tested could drastically improve the firepower of their frontline long-range artillery units, the efficiency of the operation of tactical nukes, and the diversification of their firepower missions.