North Korean leader Kim Jong-un has agreed to meet with South Korea's president next month and impose a moratorium on nuclear and missile tests if his country holds talks with the United States, a senior South Korean official said Tuesday after returning from the North.

The agreements, which follow a flurry of co-operative steps taken by the Koreas during last month's Pyeongchang Winter Olympics, brightened prospects for a dialogue between North Korea and the U.S. over the North's nuclear program.

Last year, there were increased fears of war on the Korean Peninsula, with Kim and U.S. President Donald Trump exchanging fiery rhetoric and crude insults over Kim's barrage of weapons tests.

But there is still skepticism whether the developments can help establish genuine peace between the Koreas, which have a long history of failing to follow through with major rapprochement agreements. The United States has also made it clear it doesn't want empty talks with North Korea and that all options, including military measures, remain on the table.

Trump on Tuesday reiterated his call for denuclearization of the peninsula.

Speaking during a joint news conference with visiting Swedish Prime Minister Stefan Lofven, Trump thanked Sweden for its assistance securing the release of American Otto Warmbier, who died not long after he was returned to the U.S. from detention in North Korea.

Lofven said that Sweden, which which has an embassy in Pyongyang, will do what it can to ensure any dialogue about the tensions on the peninsula goes smoothly.

On the news coming out of North Korea, Trump said he hopes the North Koreans are sincere, adding "we'll soon find out."

North Korean leader Kim Jong-un shakes hands with a member of the special delegation of South Korea's president on March 6, 2018. (KCNA/via Reuters)

Earlier, Trump praised North Korea for its participation at the Olympics.

"I thought North Korea was terrific. They came out. They went into the Olympics, they went in with good spirit. They did well … Let's see if we can carry it over," he said.

The U.S. and South Korea had agreed to a pause in joint military exercises — which rankle the North Koreans — for the Olympics and Paralympics, which begin on Thursday and run through March 18.

When asked if he'd be willing to meet with the North Korean dictator, Trump was noncommittal.

Dan Coats, Trump's director of national intelligence, said Tuesday that Washington would have to know far more before assessing North Korea's reported willingness to hold talks on denuclearization.

"Hope springs eternal, but we need to learn a lot more relative to these talks. And we will. And the IC [intelligence community] will continue to do every possible collection and assessment we can relative to the situation in North Korea. I know we'll be talking about that issue," Coats told the Senate's armed services committee hearing on worldwide threats.

South says they received nuke promise

Chung Eui-yong, South Korea's presidential national security director, said after returning from North Korea on Tuesday that the two Koreas agreed to hold their summit at a tense border village in late April. He also said the leaders will establish a "hotline" communication channel between them to lower military tensions, and would speak together before the planned summit.

Chung led a 10-member South Korean delegation that met with Kim during a two-day visit to Pyongyang, North Korea's capital. They were the first South Korean officials to meet the young North Korean leader since he took power after his dictator father's death in late 2011. Chung's trip also was the first known high-level visit by South Korean officials to North Korea in about 11 years.

Watch: Why is the Korean Peninsula divided?

The Koreas are to hold working-level talks ahead of the summit between Kim and liberal South Korean President Moon Jae-in.

If realized, it would be the third-ever such meeting since the Koreas' 1945 division. Summits in 2000 and 2007 were both held in Pyongyang between Kim's late father, Kim Jong-il, and two liberal South Korean presidents. They resulted in a series of co-operative projects that were scuttled during subsequent conservative administrations in South Korea.

Chung said North Korea also expressed willingness to hold a "candid dialogue" with the United States to discuss its nuclear disarmament and establish diplomatic relations. While such talks with the United States are underway, Chung said North Korea "made it clear that it won't resume strategic provocations like additional nuclear tests or test-launches of ballistic missiles." North Korea also said it would not need to keep its nuclear weapons if military threats against it are removed and it receives a credible security guarantee, Chung said. He said the North promised not to use its nuclear and conventional weapons against South Korea.

Analyst Cheong Seong-Chang of South Korea's Sejong Institute said the agreements "potentially pave the way for meaningful dialogue between Washington and Pyongyang," and offer an opportunity to stably manage the threat posed by North Korea's nuclear weapon and missile programs.

"Getting North Korea to agree to halt additional nuclear weapons and missile tests while the dialogue goes on is the biggest achievement of the visit to Pyongyang by the South Korean presidential envoys," he said.