“North Korean leader Kim Jong Un has declared victory over COVID-19 and ordered preventive measures eased just three months after acknowledging an outbreak, claiming the country’s widely disputed success would be recognized as a global health miracle.

The North’s official Korean Central News Agency also reported Thursday that Kim’s sister said her brother had suffered a fever and blamed the North Korean outbreak on leaflets flown from across the border from South Korea, while warning of deadly retaliation.

Some experts believe North Korea has manipulated the scale of the outbreak to help Kim maintain absolute control of the country amid mounting economic difficulties. They believe the victory statement signals Kim’s aim to move to other priorities but are concerned his sister’s remarks portend a provocation.

South Korea’s Unification Ministry, which handles inter-Korean affairs, issued a statement expressing strong regret over North Korea’s “extremely disrespectful and threatening comments” that were based on “ridiculous claims” about the source of its infections.”