North Korea imposed a nationwide lockdown on Thursday to control its first confirmed case of Covid-19 after holding for more than two years to a widely doubted claim of a perfect record in keeping out the virus. Tests of samples collected on Sunday from an unspecified number of people with fevers in Pyongyang confirmed that they were infected with the Omicron variant, AP reported, citing the official Korean Central News Agency. North Korean leader Kim Jong-un called for a thorough <a href="https://www.thenationalnews.com/world/asia/north-korea-declares-emergency-over-suspected-coronavirus-case-1.1054516" target="_blank">lockdown of cities and counties</a> and said workplaces should be isolated by units to prevent the virus from spreading, the KCNA said. North Korea has <a href="https://www.thenationalnews.com/world/asia/north-korea-attempts-pfizer-hack-to-steal-vaccine-technology-1.1167092" target="_blank">shunned vaccines offered by the UN-backed Covax</a> distribution programme, possibly because they have international monitoring requirements. As of March, no cases of Covid-19 had been reported, the World Health Organisation said. There is no official record of any North Koreans having been vaccinated. “There has been the biggest emergency incident in the country, with a hole in our emergency quarantine front, that has been kept safely over the past two years and three months since February 2020,” the KCNA said. The fact that Mr Kim called a party politburo meeting at dawn and state media immediately published the deliberation shows the urgency of the situation, said Yang Moo-jin of the University of North Korean Studies in Seoul. “Externally, there may be an indirect message of the need for co-operating with the international community if it proves to be difficult to overcome on its own,” Mr Yang said. A South Korean website that monitors activities in Pyongyang said this week that residents have been told to return home and remain indoors because of a “national problem”, without offering details. Shortly after the announcement, North Korea fired three ballistic missiles off its east coast, South Korea and Japan said. Three short-range ballistic missiles were fired at about 18.30 local time from the Sunan area of Pyongyang, where an international airport is located and where the country said it had fired its largest intercontinental ballistic missile, the Hwasong-17, on March 24, South Korea's Joint Chiefs of Staff said. The missiles flew about 360 kilometres, reaching an altitude of 90km and a maximum velocity of Mach 5, the joint chiefs said. The US military said the launch did not pose an immediate threat to it or its allies. Japanese Defence Minister Nobuo Kishi presented slightly different figures for the launch, saying the missiles flew about 350km, to the maximum altitude of about 100km, before landing outside Japan's territorial waters. “A series of missile launches when the invasion of Ukraine is taking place is unacceptable,” he told reporters and added that Tokyo had lodged a protest against North Korea through its embassy in Beijing. The launch was the first since the inauguration this week of conservative South Korean President Yoon Suk-yeol, who has signalled a hard line against the North's weapons development. Mr Yoon's national security office issued a statement condemning the launch, saying it “deplored the duplicitous conduct” of firing ballistic missiles and ignoring the plight of its people in the middle of a Covid outbreak. In its last weapons test on Saturday, the North used a submarine-launched ballistic missile, which it has been aggressively developing in recent years. Mr Kim vowed late last month to expedite the country's build-up of its nuclear arsenal amid stalled denuclearisation talks with the US. US and South Korean officials have said Pyongyang's first nuclear test since 2017 could take place as early as this month.