In the past four years, North Korea launched two suspected "short-range missiles" on Thursday, adding another complication into Pyongyang's stalled negotiations with the United States and peace talks with South Korea.
Conservatives in South Korea have launched a political offensive on President Moon Jae-in for failing to prevent the man's death.
North Korea yesterday accused South Korea of sending ships across the disputed sea boundary to find the body of a man recently killed by North Korean troops, warning Sunday the alleged intrusion could escalate tensions.
South Korea said earlier that North Korea sent an attempt to soothe anti-North sentiment in South Korea that could make it difficult for him to win concessions in any negotiations.
Kim is currently struggling to overcome worsening economic woes caused by U.S.-led sanctions over his nuclear program and the pandemic that forced his country to close its border with China, its biggest trading partner.
Government officials found a floating object in North Korean waters.
Officials in Seoul say the 47-year-old was likely to defect to North Korea, but little else is known about his motives.
"We urge the Southside to immediately halt the intrusion across the military demarcation line in the West Sea that may lead to an escalation of tensions," the official Korean Central News Agency said. "It arouses our due vigilance as it may lead to another awful incident."