The Koreas’ first high-level talks in years were scrapped a day before they were to begin on Wednesday because the sides didn’t agree on the delegation leaders, South Korea said. The cancellation deflated tentative hopes that the rivals would improve ties following years of rising hostility.

North Korea said it wasn’t sending its officials to Seoul for the two-day meeting because the South had changed the head of its delegation, Kim Hyung-suk, a spokesman for Seoul’s Unification Ministry, told reporters in a briefing on Tuesday. The ministry is in charge of North Korea matters.

The hope was that talks on reviving two high-profile economic cooperation projects would start to mend a relationship marred earlier this year by North Korean threats of nuclear war and South Korean vows of counter-strikes.

South Korea had originally wanted a minister-level meeting between the top officials responsible for inter-Korean affairs, but Pyongyang wouldn’t commit to that. The last minister-level meeting between the Koreas occurred in 2007.

When Seoul told Pyongyang on Tuesday that it was sending a lower-level official than it had initially proposed in preparatory talks, North Korea said it would consider that a “provocation,” Mr. Kim said.

The talks were set up in a painstaking 17-hour negotiating session on Sunday, but the rivals had set aside the issue of who would lead North Korea’s delegation. Mr. Kim said North Korea offered on Tuesday to send a senior official of the Committee for the Peaceful Reunification of Korea as chief delegate, and Seoul said it would send its vice-unification minister as chief delegate.

South Korea had previously proposed sending its unification minister. After it announced the vice minister would go instead, North Korea said it wouldn’t send anyone and that “all responsibility is entirely on South Korea,” Mr. Kim said. He added that Seoul is still open to talks if North Korea reconsiders.

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