"We are not going to reveal the source", said Sung Baik-you, spokesman for the Games' local organisers.
-South Korean war games that North Korea claims are preparation for invasion.
Moon shook hands with both Kim Yo Jong and Kim Yong Nam at the Olympics opening ceremony on Friday and they cheered as athletes from North and South entered the arena together behind a unification flag showing an undivided Korean peninsula.
It was the USA that appeared to be the one left in the cold, especially after the sister of the North Korean dictator extended an invitation from her brother for Moon to visit the North.
On Saturday, the presidential office announced that North Korean leader Kim Jong-un has invited President Moon Jae-in to visit Pyongyang at the earliest convenient date.
Pence has repeatedly said he would deliver a tough message to the North in any meeting.
"Chairman Kim Jong Un's envoy Kim Yo-jong delivered a letter expressing a willingness to improve relations", the presidential spokesman said.
It gives him "the rationale or the excuse to work on some moderation of the sanctions and possibly the scale and timing of the military exercises", said former South Korean Foreign Minister Han Seung-joo, in an interview. The Pences, seated next to Moon and just a row ahead of Kim and the North's 90-year-old nominal head of state, remained in their seats, unsmiling.
'Horrific murder spree' in Kentucky leaves 5 dead in 2 shootings
He also wrote on his Facebook page that the scene was 'heart wrenching, ' and said it was 'a multiple murder of family'. The Camry was then tracked to an apartment complex where three people were shot dead - two women and Nickell.
North Korea's delegation to the Winter Olympics returned to Pyongyang on Sunday, ending a three-day visit that amounted to a remarkable diplomatic breakthrough for the South Korean government but left big questions about whether it could lead to a solution to the decades-long military standoff between the two nations.
On Saturday, she sat down for almost three hours of meetings and lunch at the Blue House, South Korea's presidential complex.
Moon and Kim Yong-nam planned to return to the Games venue to watch the joint Korean women's ice hockey team - the first ever combined team at the Olympics - take on Switzerland, the Blue House said.
The athletes elicited a standing ovation by most leaders in the VIP box, including Moon and Kim's sister.
OLYMPIC officials today said a cyberattack was responsible for an internet and Wi-Fi shutdown during the Pyeongchang Winter Games opening ceremony, but refused to say who was behind it. Two players, one South Korean and the other North Korean, appeared on the opening ceremony and climbed stairs together with the Olympic torch that they handed to Olympic champion figure skater Yuna Kim.
He said the United States would take whatever "action is necessary to defend our homeland" against the North Korean nuclear threat, according to an interview with NBC.
Mr Moon is eager to use Kim Yo Jong's presence at the games to restore regular communication with North Korea and eventually pull it into nuclear talks.
It is now unclear how the unidentified Korean man was able to jump the barriers and get onto the ice chute but local police in Pyeongchang, the South Korean resort where the two week tournament is held, say they are investigating.