Key moments in Kim Jong Un's diplomatic charm offensive

North Korean leader Kim Jong Un's summit with Russian President Vladimir Putin this week expands a diplomatic charm offensive that has included meetings with leaders from China, South Korea and the United States. Some key moments:

Jan. 1, 2018: In his New Year's address, Kim calls for improved relations with South Korea and offers to send a delegation to the Winter Olympics there.

February 2018: North Korea sends hundreds of people to Pyeongchang Games in South Korea, including Kim's sister, who conveys her brother's desire for a summit with President Moon Jae-in.

March 7, 2018: After visiting Kim in Pyongyang, South Korean presidential envoy Chung Eui-yong says Kim is willing to discuss the fate of his nuclear arsenal with the United States. Days later, President Donald Trump accepts Kim's invitation to meet following a conversation with Moon's envoys.

March 27, 2018: Kim makes a surprise visit to Beijing for a meeting with Chinese President Xi Jinping in an apparent move to strengthen his leverage ahead of his negotiations with Trump.

April 21, 2018: North Korea says it has suspended nuclear and long-range missile tests and announces plans to close its nuclear test site as part of a move to shift its national focus and improve its economy. Trump tweets: "This is very good news for North Korea and the World" and "big progress!"

April 27, 2018: Kim holds a summit with Moon. The leaders announce vague aspirational goals of a nuclear-free Korean Peninsula and permanent peace.

May 7, 2018: Kim meets Xi again in China and calls for stronger strategic cooperation between the traditional allies.

May 9, 2018: U.S. Secretary of State Mike Pompeo visits Pyongyang to prepare for the planned Trump-Kim summit. North Korea releases three Americans who had been imprisoned, and they return with Pompeo to the United States.

May 24, 2018: North Korean diplomat Choe Son Hui releases a statement referring to Vice President Mike Pence as a "political dummy" for his critical comments on the North and saying it was up to the Americans whether they would "meet us at a meeting room or encounter us at nuclear-to-nuclear showdown." Trump announces he's pulling out of his summit with Kim, citing the North's "tremendous anger and open hostility."

May 26, 2018: Kim and Moon meet at a border village in an effort to revive the summit with Trump. Moon says Kim reaffirmed his commitment to denuclearize but also said he was unsure whether he could trust the United States to provide a credible security guarantee in return.

June 1, 2018: After meeting North Korean envoy Kim Yong Chol at the White House, Trump says his meeting with Kim Jong Un is back on for June 12.

June 12, 2018: Trump and Kim meet in Singapore, where they repeat the first inter-Korean summit's vague statement on the peninsula's denuclearization without describing when and how it will occur.

June 19, 2018: Kim visits Beijing for his third meeting with Xi, who praises the "positive outcome" of the Trump-Kim meeting.

Aug. 24, 2018: Trump cancels a scheduled trip to North Korea by Pompeo citing lack of "sufficient progress" on denuclearization.

Sept. 19, 2018: Kim and Moon hold their third summit in Pyongyang and the North says it's willing to permanently dismantle its main nuclear complex in Yongbyon if the United States takes unspecified corresponding measures. The Koreas also vow to resume joint economic activities when possible, voicing optimism that international sanctions could end and allow such projects.

Jan. 1, 2019: Kim in his New Year's speech says he hopes to continue his nuclear summitry with Trump, but also that he would seek a "new way" if the United States persists with sanctions and pressure against the North.

Jan. 8, 2019: Kim visits Beijing for his fourth summit with Xi, vows to "achieve results" on the nuclear standoff in his next summit with Trump.

Feb. 8, 2019: Trump announces the Vietnamese capital, Hanoi, as the venue of his second summit with Kim.

Feb. 27-28, 2019: Trump and Kim's second summit breaks down over what the Americans describe as excessive North Korean demands for sanctions relief in exchange for partial disarmament steps limited to the Yongbyon complex.

April 13, 2019: Kim says he is open to a third summit with Trump, but sets the year's end as a deadline for Washington to offer mutually acceptable terms for an agreement.

April 23, 2019: North Korea says Kim will soon visit Russia to meet with Putin.