U.S. and North Korean officials met again Monday at the demilitarized zone to talk about a possible summit between President Donald Trump and North Korean leader Kim Jung Un.

After calling off the talks Thursday, Trump said the June 12 summit in Singapore may very well take place as scheduled.

"I truly believe North Korea has brilliant potential and will be a great economic and financial nation one day," Trump said Sunday on Twitter. "Kim Jong Un agrees with me on this. It will happen."

Sung Kim, the U.S. ambassador to the Philippines and former envoy to South Korea, is leading the U.S. delegation at the preparation talks. Reports say the meetings are expected to last until Tuesday.

"We can be successful in the denuclearization of the Korean Peninsula, that would be a great thing for North Korea, it would be a great thing for South Korea, it would be great for Japan, it would be great for the world, it would be great for the United States, it would be great for China. A lot of people are working on it. It's moving along very nicely," Trump said.

After a surprise meeting Saturday between Kim and South Korean President Moon Jae-in, the Seoul leader said Kim is still committed to the "complete denuclearization" of the Korean peninsula, but he declined to define the phrase, suggesting that difficult negotiations lie ahead between the U.S. and North Korea.

The U.S. has called for "complete, verifiable, and irreversible" dismantling of the Pyongyang's nuclear arsenal, but North Korea has rejected unilateral disarmament and called for denuclearization of the Korean peninsula.

Some U.S. officials remain skeptical that the U.S.-North Korean talks would lead to the end of the North's nuclear program.

Senator Marco Rubio, a member of the Senate Foreign Relations Committee, contended on CBS News on Sunday that North Korea is "playing a game. Kim Jong Un � these nuclear weapons are something he's psychologically attached to. They are what gives him his prestige and importance. ... I'd love to see them denuclearize. I just, I'm not very optimistic about that."

James Clapper, a former U.S. director of national intelligence, also on CBS, said he worries that the North may demand the removal or scaling back of the U.S. contingent of 28,500 troops in South Korea in exchange for denuclearization, although U.S. officials have ruled out a troop withdrawal.

It is not exactly clear what made Trump change his mind about wanting to meet with Kim just a day after he called off their talks.

Trump was angered over the North's insult of Vice President Mike Pence � calling him a "political dummy" � and its threat to use nuclear force. Pence remarked last week that North Korea could wind up like Libya � a country mired in chaos since it gave up its nuclear ambitions and saw its longtime dictator killed years later by U.S.-backed rebels.

But Trump said Friday "everybody plays games," and noted North Korea's "warm and productive" reaction to his letter to Kim, canceling their talks.

North Korean state media has reported on Kim's "fixed will" that a summit with Trump should go ahead.

Moon and Kim met near the two Koreas' heavily militarized border.

The leaders exchanged views on how to prepare for the North's possible summit with Trump, the South Korean presidential office said.

After the meeting, South Korea's President Moon was upbeat.

"It was like an ordinary encounter between friends," he said. "What's uncertain for Kim is not his intention to denuclearize, but the U.S. stance in hostile relations with North Korea and whether the U.S. can really secure and guarantee his regime."

Kim thanked Moon "for much effort made by him" towards the summit, and said he hoped to improve relations with Washington and "establish mechanism for permanent and durable peace."

Leaders of North and South Korea also agreed to "meet frequently," the North's KCNA agency added.

Moon said Monday, "What's more important than anything from the latest inter-Korean summit was that the leaders easily got in contact, easily made an appointment and easily met to discuss urgent matters, without complicated procedures and formalities, just like a casual meeting."

Source: Voice of America