Seoul — As Kim Jong Un walked with the car carrying the coffin of his father, former North Korean dictator Kim Jong Il, the public displays of grief by mourners lining the funeral procession route would have reminded him that he had big shoes to fill. But a decade on, he's done it. Unforgettable pictures of the young Kim riding a horse up a sacred mountain, released by North Korea's government in 2019, depicted a man firmly in control not only of his steed, but of his country. Ryu Hun Woo was a senior North Korean diplomat until he defected from the isolated "Hermit Kingdom" two years ago. Speaking to CBS News Asia correspondent Elizabeth Palmer, Ryu said there was no ambiguity in North Korea about who was in charge. Kim has "absolute power," said the defector. "That's how he maintains the dictatorship." Kim Jong Un, as commander in chief of North Korea's armed forces, has amped-up the country's weapons program. On his watch, the North has tested four nuclear warheads, and in 2017, a missile capable of reaching the United States. His meetings with President Trump in 2018 and 2019 failed to kickstart negotiations on denuclearization in return for sanctions relief, and at the annual ruling party congress earlier this year, Kim said the U.S. remains North Korea's biggest enemy. But his other enemy is the coronavirus pandemic. Kim has sealed the country's borders for the second time in a bid to keep COVID-19 out, which means no trade, and no aid — not even donated vaccine doses. He isn't even letting in COVID vaccines made and supplied by his ally, China. Apart from a lack of syringes in the country, Ryu explains the drugs would be useless as there's no reliable electricity supply, to ensure they can be stored at the required low temperatures. However, it's not even clear they'd be needed. Kim claims there hasn't been a single case of COVID-19 in North Korea since the pandemic began. Unlikely as it sounds, it may actually be true. The borders have been shut so effectively that no one — not even the smugglers who have trafficked goods to and from China for years — is getting in or out. Nor is any information. North Korea has been a complete news void for almost two years. Defectors like Ryu, along with various intelligence services in South Korea and elsewhere, have been getting almost no reliable updates about what is really going on inside the North. The grand military spectacles that Korea regularly stages have continued during the pandemic, but they mask North Korea's suffering. Back in June, at a meeting of the ruling Workers' Party's Central Committee, Kim himself acknowledged that food scarcity loomed. "The people's food situation is now getting tense," he said, admitting that typhoons had damaged the country's grain crop. Analysts think it's likely that people are going hungry this winter. Kim Jong Un will mark the end of his first decade in power armed to the teeth, but more isolated than ever as he tries to battle a killer virus in one of the world's poorest countries. He's no closer to what he really wants, which is relief from devastating sanctions and normal relations with the rest of the world.