Photo/IllutrationSouth Korean President Moon Jae-in talks with Kim Yo Jong, North Korean leader Kim Jong Un's sister, during a performance of North Korea's Samjiyon Orchestra at National Theater in Seoul on Feb. 11. At left is Kim Yong Nam, North Korea's nominal head of state. (Yonhap via AP)

SEOUL--Officials from South Korea secretly traveled to Pyongyang at least twice late last year to coordinate North Korea's participation in the Pyeongchang Winter Olympics, a move that later miffed the United States, sources said.

Such visits are extremely rare as South Korea, in principle, prohibits exchanges with North Korea.

The United States was irritated by the initiative, which led U.S. Vice President Mike Pence to reject contacts with North Korean delegates when he visited South Korea earlier this month, they added.

According to the sources, South Korea first sounded out North Korea about holding hush-hush meetings, viewing the Olympics as a good opportunity to improve bilateral relations.

In November or later, South Korean officials visited North Korea via China to hold talks.

As a condition for its participation, North Korea demanded the suspension of a joint military drill to be conducted by the United States and South Korea, which Seoul rejected.

However, the allied military forces had concluded last autumn it would not be realistic to hold a joint military drill while the Games were in progress.

South Korean President Moon Jae-in revealed in an interview with the U.S. National Broadcasting Co. on Dec. 19 that South Korea had asked the United States to reschedule the joint drill to after the Olympics and Paralympics had finished.

North Korea was unhappy about the postponement, but eventually decided to take part in the sports extravaganza.

On Jan. 1, North Korean leader Kim Jong Un announced in a new year speech that talks were planned with South Korea about Pyongyang dispatching athletes and delegates to the Pyeongchang Olympics.

During the secret contacts, South Korea apparently asked North Korea to reduce the scale of its military parade that was expected in Pyongyang on Feb. 8. South Korea also requested that North Korea send a delegation of high-ranking officials to South Korea.

Pyongyang proposed that Kim Yo Jong, younger sister of the North Korean leader, accompany the Olympic delegation to South Korea, the sources said.

On Feb. 19, the South Korean presidential office issued an official denial of any secret meeting in Pyongyang between the two countries.