South Korean President Moon Jae-in urged the United States to "lower the threshold for talks" with North Korea on Monday as his aides held rare talks with a Pyongyang general on ways to defuse tensions.
Moon has sought to use the Pyeongchang Winter Olympics that ended on Sunday to open dialogue between Washington and Pyongyang in the hopes of easing a nuclear standoff that has sparked global security fears.
Pyongyang mounted a charm offensive during the Games, sending athletes, cheerleaders and performers.
The North's leader Kim Jong Un also sent his sister to attend the opening ceremony before dispatching Kim Yong Chol, a powerful general in charge of inter-Korea affairs for the ruling Workers' Party, to Sunday's closing event.
But there was no known interaction between the North and the US during the Games and Washington on Friday imposed what US President Donald Trump described as the "heaviest ever" sanctions on the isolated regime.
"I think the US needs to lower the threshold for talks and the North also needs to show determination for denuclearisation," Moon said in a meeting with Liu Yandong, a Chinese envoy to the closing ceremony.
"It's important that the US and the North sit together as soon as possible," Moon said, urging efforts by Beijing to make that happen.
Moon, in a meeting with Kim Yong Chol on Sunday, also urged the North to open dialogue with the US as soon as possible - to which Kim responded by saying the North was "very willing" to hold talks.
But the US has ruled out any possibility of talks before Pyongyang, which last year staged multiple missile and nuclear tests, takes steps towards denuclearisation.
"We will see if Pyongyang's message today, that it is willing to hold talks, represents the first steps along the path to denuclearisation," the White House said in a statement.
"The maximum pressure campaign must continue until North Korea denuclearises," it said.
Trump and Kim Jong Un have traded threats of war and colourful personal insults, prompting concerns over a potential conflict on the flashpoint peninsula once left in ruins after the 1950-53 Korean War.
Kim Yong Chol also met Moon's top aides including national security adviser Chung Eui-yong on Monday as conservative demonstrators denounced his presence in the South.
During the meeting, Kim reiterated that the "doors are open for dialogue with the US," according to Moon's office.
Kim is accused of masterminding deadly attacks on the South, including the 2010 sinking of a South Korean warship that left 46 dead. Seoul accused Pyongyang of torpedoing the ship, a charge the North denies.
Dozens of activists held a protest near the luxury Seoul hotel where Kim and seven other North Korean delegates are staying, ripping apart the general's portrait and torching the North's national flag.
Hundreds of conservative lawmakers and their supporters also held a separate protest in Seoul, waving banners saying "Arrest Kim Yong Chol!" among other slogans.
"Kim Yong Chol is nothing but a murderer!" Hong Joon-pyo, the leader of the conservative opposition Liberty Korea Party, said during the protest. "And our commander-in-chief is rubbing shoulders with him!"