• Improving inter-Korean ties are eclipsing the gradual pace of denuclearization in North Korea, some experts warn.
  • South Korean President Moon Jae-In has long advocated a policy of engagement and detente toward Pyongyang.
  • "Rapid inter-Korean rapprochement is badly out of sync with the stalemate on the nuclear track," Daniel Russel, former U.S. assistant secretary of state for East Asian and Pacific affairs, said in October.
South Koreans watch a television broadcast reporting the South Korean President Moon Jae-in meeting with North Korean Leader Kim Jong Un, at the Seoul railway station on September 18, 2018 in Seoul, South Korea. 

South Korea's desire to engage and unify with its reclusive northern neighbor appears to be clashing with Washington's goal of eliminating nuclear weapons on the Korean Peninsula.

As the two Koreas make steady progress toward reconciliation — a South Korean train on Friday traveled across the border into the North for the first time in a decade — there are mounting concerns that peace efforts may overshadow the denuclearization of North Korea.