President Donald Trump and French President Emmanuel Macron (not shown) during their meeting in the Cabinet Room of the White House in Washington, Tuesday, April 24, 2018.

President Donald Trump on Tuesday said North Korean dictator Kim Jong Un has been "very open" and "very honorable," and wants an historic, high-stakes meeting as soon as possible.

This is a sharp break from the American president's previous denunciations of Kim Jong Un as "Little Rocket Man."

The United States and North Korea have been negotiating a summit between Trump and Kim Jong Un to be held in May or June to broker a deal on Pyongyang's nuclear ambitions. Trump, who has struck a decidedly optimistic tone on the situation in recent days, said Tuesday that the United States and North Korea were having "good discussions."

"We have been told directly that they would like to have the meeting as soon as possible. We think that's a great thing for the world," Trump said at the White House alongside French President Emmanuel Macron. "Kim Jong Un, he really has been very open and I think very honorable from everything we're seeing."

Trump cautioned that North Korea had not followed through on previous promises, but credited tough steps from his administration — including sanctions and organizing pressure from international allies — for having forced Pyongyang to hold talks. And he again suggested that he would "leave the table" if they negotiations were not productive or if North Korea was not operating in good faith.

"We'll see where that all goes," the president said. "Maybe it will be wonderful or maybe it won't."

Trump's comments came days after a flurry of signs from North Korea that the White House was anxious to promote as signs that its coercion campaign was working. On Saturday, North Korea announced it will close its nuclear testing facility and suspend nuclear and intercontinental ballistic missile tests — a move welcomed by Trump as "big progress."

However, the North stopped short of suggesting it will give up its nuclear weapons — as Trump suggested in a tweet — or scale back its production of missiles and their related components.

Asked if the suspension of tests was a positive sign, Defense Secretary Jim Mattis said Monday, "Right now, I think there (are) a lot of reasons for optimism that the negotiations will be fruitful and we'll see."

This week, U.S.-allied South Korean President Moon Jae-in and Kim will hold a summit in the demilitarized zone between the Koreas that could lay the ground for Trump's planned meeting with the North Korean dictator. The leaders of the U.S. and North Korea have never met during six decades of hostility since the Korean War.

The exact date and location of the possible summit has not been determined.

White House press secretary Sarah Huckabee Sanders said Monday that the U.S. goal was the complete denuclearization of the Korean Peninsula. When asked if the president was willing to accept anything short of that goal before lifting sanctions or was willing to go incrementally, she told reporters: "Certainly no sanctions lifted until we see concrete actions taken by North Korea to denuclearize."

Last year, the U.S. spearheaded through the U.N. Security Council the toughest international sanctions yet against North Korea in response to three long-range missile launches and its most powerful nuclear test explosion yet. The Trump administration supplemented those restrictions with unilateral U.S. sanctions against firms that had conducted illicit trade with the North.

This year, Kim has pivoted from confrontation to diplomacy and, according to South Korea and China, has expressed a commitment to denuclearization. There is still uncertainty about what he seeks in return.

Trump's praise for Kim Jong Un on Tuesday stood in stark contrast to his previous bellicose rhetoric toward the North Korean leader. Beyond dubbing him "Little Rocket Man" from the rostrum of the United Nations last fall, Trump has threatened to deliver "fire and fury" upon North Korea and taunted Kim Jung Un on Twitter that his nuclear "button" was larger than the one in Pyongyang.