Ahead of the talks, CNBC takes a look at some of the most memorable quotes from Kim Jong Un over the past 12 months

While Kim Jong Un has ignored recent peace overtures with Seoul, officials from both countries are expected to initiate a formal dialogue on Tuesday

North Korea's leader is thought to have turned 35, although the state does not publicly recognize his birthday and there is no mention of the date on the regime calendar

This undated picture released from North Korea's official Korean Central News Agency (KCNA) on September 12, 2017 shows North Korean leader Kim Jong-Un (C) attending a photo session with teachers who volunteered to work at branch schools on islands and schools in forefront line and mountainous areas, in Pyongyang. STR | AFP | Getty Images

North Korea's Kim Jong Un was widely believed to be celebrating his birthday on Monday, a day before Pyongyang is set to hold talks with its southern neighbor for the first time in more than two years. The leader is thought to have turned 35, although the North Korean state does not publicly recognize his birthday and there is no mention of the date on the regime calendar. While Kim Jong Un has ignored recent peace overtures with Seoul, officials from both countries are expected to initiate a formal dialogue on Tuesday. Ahead of the talks, CNBC takes a look at some of the most memorable quotes from Kim Jong Un over the past 12 months.

North Korea has 'achieved' nuclear status

In his 2017 New Year's address, North Korea's leader claimed the country had "achieved the status" of a nuclear power, before adding economic rivals would no longer dare to provoke a "military giant in the East." In response to Kim Jong Un's claim his country had the capacity to launch intercontinental ballistic missiles that could reach the U.S., President Donald Trump tweeted: "It won't happen."

'Up to you whether the US exists on this planet'

In a state-produced video released last March, images showed a computer-animated nuclear attack on Washington. Subtitles to the video warned that the U.S. would be punished if it continued to provoke Pyongyang, before adding: "The United States must choose! It's up to you whether the nation called the United States exists on this planet or not."

North Korean soldiers attend a mass rally to celebrate the North's declaration on November 29 it had achieved full nuclear statehood, on Kim Il-Sung Square in Pyongyang on December 1, 2017. KIM WON-JIN | AFP | Getty Images

The United Nations (UN) had imposed sanctions on North Korea earlier that month, after the country tested a nuclear device and a long-range rocket.

'Bereft of reason'

In August, amid escalating tensions between North Korea and the U.S. regarding Pyongyang's nuclear missile tests, North Korea's military warned "only absolute force can work" when communicating with the U.S. leader. "Sound dialogue is not possible with such a guy bereft of reason," Kim Jong Un said in a statement published on Korea's state run news agency.

'Mentally deranged US dotard'

Trump issued a harsh warning at the UN General Assembly to nuclear-armed North Korea in September. In his first address, Trump threated to "totally destroy" Pyongyang if the U.S. was prompted to defend itself or its allies.

President Donald Trump. Kena Betancur | AFP | Getty Images

"Whatever Trump might have expected, he will face results beyond his expectation. I will surely and definitely tame the mentally deranged U.S. dotard with fire," Kim Jong Un said in a statement circulated on state news agency KCNA. Translated from Korean to English, the word "dotard" generally means an imbecile.

'Nuclear button on my desk'