Timeline: North Korea-US summit goes through many twists and turns The three leaders involved have gone back and forth on planned talks.

SEOUL, South Korea -- Just four days remain until two of the world's most unpredictable leaders sit down at a historic summit.

Next Tuesday, President Donald Trump will sit across from North Korean leader Kim Jong Un in a gesture intended to open his hermit kingdom to the rest of the world.

The United States announced on May 10 that a summit between Trump and Kim Jong Un would take place June 12 in Singapore. As new Secretary of State Mike Pompeo returned earlier the same day from a visit to Pyongyang, bringing back three American detainees, the U.S.-North Korea relationship seemed to be proceeding smoothly.

But diplomatic peace did not last long. North Korea threatened to pull back from summit and criticized the U.S. with typical, fiery North Korean statements. As a response, Trump actually canceled the summit with a letter. But with a North Korean envoy hand-delivering a letter from Kim to Trump, the summit is back on.

We break down the complicated back-and-forth since the initial announcement.

Timeline:

May 15 (11 a.m. EDT): North Korea suspends high-level inter-Korean talks. The North originally requested the meeting, but cancelled with less than 10 hours until the rendezvous. The North criticized the South for carrying out joint U.S.-South Korea military drill, Max Thunder. North’s state media called it a "North invasion uproar."

May 15 (evening EDT): North Korea’s state media made a statement under Vice Foreign Minister Kim Kye Kwan’s name. It said the United States was pressuring North Korea to give up nuclear power from one side. The statement called National Security Adviser John Bolton "repugnant," due to his comparison of North Korea to Libya.

May 22: U.S. Vice President Mike Pence warned North Korea in an interview with Fox News: "There was some talk about the Libyan model last week, and you know, as the president made clear, this will only end like the Libyan model ended if Kim Jong Un doesn't make a deal."

May 22: South Korean President Moon Jae-in and Trump met in Washington.

May 24 (7:40 p.m. EDT): A statement made under name of Choi Son Hui, the vice foreign minister of North Korea, called Pence a "political dummy": "In case the U.S. offends against our goodwill and clings to unlawful and outrageous acts, I will put forward a suggestion to our supreme leadership for reconsidering the DPRK-U.S. summit."

May 24: North Korea goes through with destroying its nuclear testing facility at Punggye-ri as promised.

May 24: Trump calls off the planned summit with Kim Jong Un. In his official signed letter he says, "Based on the tremendous anger and open hostility displayed in your most recent statement, I feel it is inappropriate, at this time, to have this long-planned meeting." Trump left open a door for North Korea by saying chairman Kim Jong Un could contact him if he changes his mind on summit: "If you change your mind having to do with this most important summit, please do not hesitate to call me or write."

May 25 (Korean time): Kim Kye Kwan’s statement comes out in a calmer tone: "We would like to make known to the U.S. side once again that we have the intent to sit with the U.S. side to solve the problem regardless of ways at any time."

May 25: Trump says, "If the U.S.-North Korea summit happens, it will be in Singapore on June 12."

May 26 (2 a.m. EDT): A second inter-Korean summit takes place between Moon and Kim Jong Un at Tongilgak, a building on the northern side of Panmunjom. Within 12 hours, leaders from both Koreas communicated on issues related to the U.S.-North Korea summit.

May 26 (9 p.m. EDT): Moon made an announcement in front of press about his Saturday summit with Kim Jong Un, saying the meeting will "turn out fine." Meanwhile, in Washington, Trump told reporters, "We're looking at June 12 in Singapore. It hasn't changed." He said a team from the U.S. will travel to Singapore in case the summit happens.

May 28: Kim Chang Son, known as North Korea’s chief of staff, arrived in Singapore to prepare protocol.

May 30: North Korean envoy Kim Yong Chol arrived in New York. He met Pompeo in the Corinthian Condominium, a U.S. diplomatic residence. They talked over dinner banquet from 7 p.m. for 90 minutes.

May 31: In New York, Kim Yong Chol and Pompeo met starting 9 a.m. at the Corinthian Condominium. “In my conversations with Chairman Kim Jong Un in Pyongyang and today with Vice Chairman Kim Yong Chol, I have been very clear that President Trump and the United States' objective is very consistent and well known: the complete, verifiable and irreversible denuclearization of the Korean Peninsula,” Pompeo said in a briefing following the talks. “President Trump has also made it clear that if Kim Jong Un denuclearizes, there is a brighter path for North Korea.“

In North Korea, Kim Jong Un met with Russia’s Foreign Minister Sergei Lavrov and reaffirmed the communist nation’s will for denuclearization.

At the Korean border village of Panmunjom, officials from the U.S. and North Korea, including the U.S. Ambassador to the Philippines Sung Kim and North Korea’s Vice Foreign Minister Choe Son Hui, met for the second time, following the first discussion on May 27. Sung Kim is known as an experienced nuclear negotiator.

In Singapore, Deputy White House Chief of Staff Joe Hagin discussed logistics with North Korea's Kim Chang Son, North Korea's chief secretary of the Secretariat of the State Affairs Commission.

June 1: The story changed on Tuesday, when Trump said the meeting was back on: “We're meeting with the chairman on June 12 and I think it's probably going to be a very successful, ultimately a successful process.” This happened only a week after he called off the meeting with a letter. North Korean envoy Kim Yong Chol hand-delivered a letter from Kim Jong Un to Trump. For 90 minutes, the two discussed core issues at the White House.

Trump brought up declaring an end to the Korean War in front of reporters following the meeting with Kim Yong Chol. “Can you believe that we’re talking about the ending of the Korean War?” Trump said, standing right next to the North Korean envoy. He emphasized the historic significance of declaring end to the 70-year-long war.

June 2 to June 4: Follow-up, working-level discussions regarding the Singapore summit continued between U.S. and North Korean officials at Panmunjom. The first meeting came on May 27, a second on May 30 and then three days in a row from Saturday to Monday.

June 5: Singaporean Foreign Minister Vivian Balakrishnan met U.S. Secretary of State Mike Pompeo in Washington D.C. Balakrishnan was confident Singapore would serve as a neutral host. "It's in a sense of our contribution to world peace," he said.

June 6: U.S. and North Korean counterparts gathered in Panmunjom for a working-level discussion. This was the sixth time they met since first meeting May 27.

June 7: Singapore Foreign Minister Vivian Balakrishnan flew to Pyongyang for a two-day visit. Ri Yong Ho, president of the Supreme People's Assembly, greeted him.

June 8: Korean Central News Agency reported that Ri Yong Ho and Vivian Balakrishnan had a ministerial talk.