North Korean officials didn’t show up for a planned meeting with U.S. counterparts to discuss returning the remains of American war dead, South Korean media reported, in the latest sign of tensions between the two sides.

U.S. negotiators arrived Thursday at the militarized border between the two Koreas as previously announced by U.S. Secretary of State Mike Pompeo and were kept waiting, the Yonhap News Agency reported, citing diplomatic officials it didn’t identify. The meeting was expected to be the first working-level talks between the two sides since Pompeo’s visit to Pyongyang ended Saturday with North Korea denouncing the U.S.’s “unilateral and gangster-like demand for denuclearization.”