N.Korea has not conducted nuclear or long-range missile tests since 2018, but reports suggest they have been building up nuclear capabilities.
In March 2020, the New York Times reported that North Korea fired two short-range ballistic missiles off its east coast, making it North Korea’s fourth missile test in March 2020. The missiles were fired from the port city of Wonsan, flying about 140 miles to the northeast before landing in waters between North Korea and Japan.
In June 2020, Arms Control Association released a blog post stating that North Korean leader Kim Jong Un presided over a meeting of the Seventh Central Military Committee of the Worker’s Party of Korea on May 24, and discussed national efforts to bolster the country’s armed forces, including ‘new policies for further increasing the nuclear war deterrence of the country and putting the strategic armed forces on high alert.’ It further stated that the Korean Central News Agency did not provide details on what specific steps North Korea will take to strengthen its nuclear deterrent.
Furthermore, the Guardian reported in August 2020 that according to a confidential report of the UN, North Korea is pressing on with its nuclear weapons programme and several countries believe it has 'probably developed miniaturised nuclear devices to fit into the warheads of its ballistic missiles.'