SEOUL, South Korea (AP) -- After years of refusal, North Korean leader Kim Jong Un is willing to discuss the fate of his atomic arsenal with the United States and has expressed a readiness to suspend nuclear and missile tests during such talks, a senior South Korean official said Tuesday. "They seem to be acting positively," President Donald Trump said as the world awaited his next move.

Kim also agreed to meet with South Korea's president next month, South Korean presidential national security director Chung Eui-yong said after returning from rare talks with the enigmatic dictator, believed to be in his mid-30s, in the North Korean capital of Pyongyang.

North Korea's willingness to hold a "candid dialogue" with the United States to discuss denuclearization and establish diplomatic relations follows a year of increased fears of war on the Korean Peninsula, with Kim and Trump exchanging fiery rhetoric and crude insults over Kim's barrage of weapons tests. The Trump administration also pushed through some of the harshest sanctions any country has ever faced.

Trump tweeted Tuesday that "possible progress" was being made in the talks with North Korea, and that all sides were making serious efforts. He added: "May be false hope, but the U.S. is ready to go hard in either direction!"

Later he said that progress with North Korea "would be a great thing for the world." But he added, "We're going to see."

There is still skepticism whether the developments will 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 made it clear that it doesn't want empty talks with North Korea and that all options, including military measures, remain on the table.

The North has repeatedly said in the past that it won't negotiate over its nuclear program and vowed to bolster its nuclear and missile arsenals, at least while facing what it describes as an existential American threat. Its apparent about-face might be an attempt to win concessions as its economy struggles under the weight of sanctions, some analysts said, or a way to buy time to better develop nuclear missiles targeting the mainland United States.

"We have seen nothing to indicate ... that he would be willing to give up those weapons," Dan Coats, the director of U.S. national intelligence, told a Senate Armed Services Committee hearing on Tuesday. He said he could not adequately assess the South's account of the Pyongyang talks until the South Koreans have provided a full briefing.

Chung led a 10-member South Korean delegation on a two-day visit to North Korea. 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.

If talks with the United States happen, Chung said North Korea "made it clear that it won't resume strategic provocations like additional nuclear tests or test launches of ballistic missiles" while the talks continue. Such a pause in testing has been a central demand of the Trump administration for a negotiation.

Washington also wants the talks to focus on an eventual end of the North Korean nuclear threat.

There may have been progress on that front, too. North Korea told the South Korean envoys that 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.

In a sign of an increasingly pragmatic North Korean approach, Kim also said he "understands" that contentious annual military drills by the U.S. and South Korea will take place in April at a scale similar to previous years and expressed hope they could be modified once the situation on the Korean Peninsula stabilizes, according to a senior South Korean presidential official, who didn't want to be named, citing office rules.

Chung said the two Koreas agreed to hold their summit at a Seoul-controlled facility. He said Kim and South Korean President Moon Jae-in will establish a "hotline" communication channel to lower military tensions, and would speak together before the possible summit.

If realized, the summit between the countries' leaders would be the third since the Koreas' 1945 division. The two past summits, in 2000 and 2007, were both in Pyongyang and were held between Kim's late father, Kim Jong Il, and two liberal South Korean presidents. They resulted in a series of cooperative projects that were scuttled during subsequent conservative administrations in South Korea.

Analyst Cheong Seong-Chang at South Korea's Sejong Institute said new agreements "potentially pave the way for meaningful dialogue between Washington and Pyongyang" and could be the basis for easing tensions.