WASHINGTON -- North Korea is reportedly ready to talk about giving up its nuclear arsenal in what President Trump is calling a positive development in relations with Kim Jong Un. The report comes from a South Korean delegation who just returned from the first-ever talks with the North Korean leader.

"One way or the other we have to do something. We cannot let that situation fester. We cannot let it happen," Mr. Trump said.

Possible progress being made in talks with North Korea. For the first time in many years, a serious effort is being made by all parties concerned. The World is watching and waiting! May be false hope, but the U.S. is ready to go hard in either direction! — Donald J. Trump (@realDonaldTrump) March 6, 2018

In an Oval Office meeting with the Swedish prime minister, Mr. Trump expressed cautious optimism about North Korea's apparent willingness to negotiate.

Mr. Trump responded to reporter questions about the apparent easing of tensions.

"We're gonna see. We're gonna see," he said Tuesday. "They seem to be acting positively. I think their statement and the statements coming out of South Korea and North Korea have been very positive. That would be a great thing for the world. Great thing for the world. So we'll see how it comes about."

"I'd like to be optimistic, but I think maybe this has gone further than anyone has taken it before," Mr. Trump said. "Hopefully it will go in the very, very peaceful, beautiful path. We're prepared to go whichever path is necessary. I think we're having very good dialogue."

Following a meeting in Pyongyang between Kim and senior South Korean officials, South Korea said in a statement that "the North expressed its willingness to hold a heartfelt dialogue with the United States on the issues of denuclearization and normalizing relations." The statement also said the North would halt its nuclear program while negotiations were ongoing.

Later at a press conference, the president was asked why Kim may have had a change of heart.

"Me. No. Nobody got that. I think that they are sincere, but I think they are sincere also because the sanctions and what we're doing with respect to North Korea, including the great help that we've been given from China," Mr. Trump said. "The sanctions have been very, very strong and very biting."

A combination photo shows a Korean Central News Agency (KCNA) handout of Kim Jong Un released on May 10, 2016, and Donald Trump posing for a photo in New York City, on May 17, 2016. Reuters

Tough sanctions aside, it's been Mr. Trump's tough rhetoric that has helped stoke fears of a conflict on the Korean Peninsula.

"They will be met with fire and fury and frankly power, the likes of which this world has never seen before," Mr. Trump said last year.

"Rocket Man is on a suicide mission for himself and for his regime," he told the United Nations.

Ian Bremmer, president of Eurasia Group and a CBS News consultant, weighed in on the situation.

"On North Korea, there is no question the Trump administration has moved the needle from Beijing and therefore now from Pyongyang in a way that neither of the previous administrations -- Democratic or Republican -- have been able to do," Bremmer said.

On Capitol Hill, the Director of National Intelligence Dan Coats said we've seen this movie before.

The problem with North Korea is not talking or reaching agreements, but rather it is North Korea's history of breaking those deals and advancing its nuclear weapons and ballistic missile programs. As such, the U.S. and South Korea said Tuesday the prospect of talks with the North will stop joint military exercises due to begin in two to three weeks.