This came amid Kim's pledge to hold more summits with South Korea's Moon Jae-in next year to achieve the goal of denuclearisation of the Korean peninsula.
In an attempt to start working-level negotiations, the US said it would review its policy on humanitarian aid to North Korea. The Blue House didn't fully disclose Kim's letter.
Earlier this month, North Korea told the USA that sanctions and pressure won't work to force Pyongyang into action on its nuclear program.
The leader of the isolated North met Moon three times this year, twice at the border truce village of Panmunjom and once in Pyongyang, as a reconciliatory push gathered pace.
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Officials warned that two more sections of the Soviet-era block were in danger of collapsing. Another four people, including two children, were hospitalized, officials said .
But the US maintains it will keep sanctions in place against North Korea.
Kim Jong-un also expressed "regret" that a much-anticipated visit to Seoul did not materialize this year. On Feb. 10, Kim's sister Yo-jong, the first vice-director of the North's Workers' Party Central Committee, delivered a letter to Moon at Cheong Wa Dae when she visited the South to participate in the PyeongChang Winter Olympics.
According to Reuters, Kim sent a letter to Moon on Sunday to commemorate the dramatic detente they engineered this year, including three summits, after years of confrontation marked by a series of the North's nuclear and missile tests.
Kim also urged the North Korean people to strengthen their "self-reliance", a message that echoed Chinese President Xi Jinping's similar address Monday night.
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In January 2017, Trump signed an executive order that initiated the process of building a wall along the US-Mexico border. CBP said in the statement that it needs the help of other government agencies to provide health care.
The stalled negotiations have had an impact on inter-Korean ties, with Kim failing to visit Seoul this year as agreed to at an inter-Korean summit in Pyongyang in September.
The North Korean leader reached out to the South on Sunday night, . expressing his determination to make big strides toward denuclearization in 2019.
"The New Year's Day speech will likely address implementation of peace and prosperity, the denuclearization issue and maintaining the inter-Korean relations", South Korean Unification Ministry spokesman Baik Tae Hyun told a briefing.
In June, Kim vowed to work towards denuclearisation at his landmark summit with US President Donald Trump in Singapore but the two sides have since made little progress, struggling to reschedule a high-level meeting abruptly called off in November.
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Secretary of State Mike Pompeo and senior North Korean officials after the North canceled it at the last minute in November. He also called for South Korea and the USA to end joint military exercises which Kim described as "a source of tension".
Post-summit nuclear talks between Washington and Pyongyang quickly settled into a stalemate as the countries struggled between the sequencing of the North's disarmament and the removal of US -led worldwide sanctions against the North.