SEOUL, South Korea (AP) — A South Korean newspaper reported Friday that North Korea executed a senior envoy involved in nuclear negotiations with the U.S. as well as four other high-level officials. But as ever with North Korea, a country that closely guards its secrets, there are reasons to be cautious about the purported purge.

While North Korea hasn't used its propaganda services to comment, the report in the conservative Chosun Ilbo daily could be true. North Korea has previously executed scapegoats to atone for high-profile political flops, and the most recent summit between leader Kim Jo...