Trump and Kim Jong Un's planned meeting draws praise from China, Russia, Japan Tillerson said earlier that U.S. 'a long way' from negotiations with N. Korea.

President Donald Trump's plan to meet face-to-face with North Korea's Kim Jong Un elicited expressions of cautious optimism from some of the countries that may have the most at stake from Pyongyang's nuclear program.

"Meeting being planned!" Trump tweeted late Thursday ET, just hours after he spoke to South Korean National Security Director Chung Eui-yong, who made the blockbuster announcement.

Chung said the American president "will meet Kim Jong Un by May to achieve permanent denuclearization."

And neighboring countries welcomed the announcement.

In China, Foreign Ministry spokesperson Geng Shuang told reporters that Beijing "welcomes these positive signals" and hopes "all parties could show their political courage."

Japanese Prime Minister Shinzo Abe, who spoke to Trump on Thursday night, said Friday that he appreciated “North Korea’s change."

“We will continue imposing the utmost pressure until North Korea takes specific actions toward thorough, verifiable, and irreversible denuclearization,” Abe said, while also emphasizing that “Japan and the U.S. have been and will be together 100 percent.”

Russian Foreign Minister Sergey Lavrov also welcomed the announcement, telling state news agency Tass that Russia sees the planned meeting this as a "a step in the right direction."

And, in Seoul, South Korea, a spokeswoman for President Moon Jae-in characterized the development as “another great breakthrough.”

Trump's chief diplomat, Secretary of State Rex Tillerson, speaking to reporters today during his weeklong swing through Africa, said the meeting came about because of a “dramatic” change in posture by Kim Jong Un.

"I think this was the most forward-leaning report that we've had in terms of Kim Jong Un's not-just willingness but his strong desire for talks," Tillerson said in Djibouti. "So I think really what changed was his posture -- in a fairly dramatic way in all honesty -- that came as a little bit of a surprise to us as well that he was so forward-leaning in his conversations with the delegation from South Korea."

A day earlier, hours before the announcement of the planned meeting, Tillerson had told reporters, “In terms of direct talks with the United States... we're a long ways from negotiations" with North Korea.

On Friday, he sought to explain his comments the day before, drawing a distinction between talks and negotiations with Pyongyang.

"With respect to talks with North Korea versus negotiations, and I think this seems to be something that people continue to struggle with the difference, my comments have been that the conditions are not right for negotiations," the secretary of state told reporters.

He continued: "We've been saying for some time that we're open to talks. President Trump has said for some time that he was open to talks and he would willingly meet with Kim Jong Un when conditions were right, the time was right. And I think in the president's judgment that time has arrived now."

"So, no surprise," Tillerson added.

Undersecretary of State Steve Goldstein said today that Tillerson participated in the White House call with Japanese leader Abe on Thursday.

"He was kept fully informed of yesterday’s White House meetings as they progressed," Goldstein said.

Meanwhile, in South Korea, the foreign minister says her government is consulting with the United States on the details of the high stakes tête-à-tête.

"The exact timing and the place will need a lot of consideration," Foreign Minister Kang Kyung-wha said Friday while on an official visit to Hanoi, Vietnam.