The following is a chronology of major developments leading to Tuesday's announcement of a second summit between U.S. President Donald Trump and North Korean leader Kim Jong-un.

Feb. 25, 2018 -- Kim Yong-chol, a close aide to the North Korean leader, expresses an openness to talks with the United States in a meeting with South Korean President Moon Jae-in, while visiting the South for the closing ceremony of the PyeongChang Winter Olympic Games.

March 8, 2018 -- Chung Eui-yong, South Korea's presidential national security adviser, announces after a meeting with Trump at the White House that the U.S. president has agreed to meet Kim in May.

March 25-28, 2018 -- Kim makes his first visit to China since assuming power and meets with Chinese President Xi Jinping.

March 31-April 1, 2018 -- U.S. Central Intelligence Agency Director Mike Pompeo visits Pyongyang and meets with Kim to lay the groundwork for the first Trump-Kim summit.

April 27, 2018 -- Moon holds his first summit with Kim at the inter-Korean border village of Panmunjom.

May 9-10, 2018 -- Pompeo, now the U.S. secretary of state, makes his second trip to North Korea to discuss denuclearization and bring home three Korean-American detainees released by Pyongyang.

May 10, 2018 -- Trump announces on Twitter that the first-ever U.S.-North Korea summit will be held in Singapore June 12.

May 22, 2018 -- Moon and Trump hold talks in Washington.

May 24, 2018 -- North Korea demolishes its nuclear testing site in Punggye-ri in front of a group of international reporters.

Trump, Kim to meet in Vietnam on Feb. 27-28 2019-02-06 17:01  |  Politics
May 24, 2018 -- Trump cancels the summit over what he calls "open hostility" in North Korean officials' remarks toward Washington.

May 26, 2018 -- Moon and Kim hold an unannounced second summit in Panmunjom.

May 31, 2018 -- Pompeo and Kim Yong-chol hold talks in New York.

June 1, 2018 -- Kim Yong-chol delivers a letter from the North Korean leader to Trump at the White House, after which the U.S. president announces the summit is back on for June 12 in Singapore.

June 12, 2018 -- Trump and Kim hold a historic summit in Singapore, the first meeting between sitting leaders of the two countries, and produce a joint statement committing the sides to complete denuclearization of the Korean Peninsula, U.S. security guarantees for the North and the return of American troops' remains.
Trump also tells a press conference that he is suspending South Korea-U.S. military exercises to facilitate negotiations with the North.

Aug. 23, 2018 -- Pompeo appoints former Ford Motor executive Stephen Biegun as the U.S. special representative for North Korea.

Sept. 10, 2018 -- The White House says Kim has requested a second summit, in a letter to Trump, and the two sides are working on details.

Oct. 7, 2018 -- Pompeo makes his fourth trip to Pyongyang, accompanied by Biegun. The envoy later reveals that Kim committed to dismantling and destroying all plutonium and uranium enrichment facilities in exchange for "corresponding measures" from the U.S.

Jan. 1, 2019 -- Kim says in his annual New Year's address that he ready to meet Trump again at any time.

Jan. 17-19, 2019 -- Kim Yong-chol visits Washington for talks with Pompeo and Trump. The White House announces the second summit will be held near the end of February at a location to be announced in the future.

Jan. 31, 2019 -- Biegun makes a public speech at Stanford University, saying the U.S. is ready to discuss "corresponding measures" for North Korea's denuclearization.

Feb. 5, 2019 -- Trump announces the second summit will be held in Vietnam Feb. 27-28. (Yonhap)