Some experts caution that it is only a matter of time before North Korea completes its nuclear force. By mid-2022, satellite imagery showed that construction had advanced, and the IAEA expressed concern that North Korea was preparing for a seventh nuclear test. But in August 2021, the International Atomic Energy Agency (IAEA) reported that North Korea had again started producing fissile material at Yongbyon. In 2018, North Korea said it shut down its main nuclear-material production site, the Yongbyon reactor complex, following the country’s summits that year with the United States and South Korea. North Korea has not conducted a nuclear test since then. An explosion of such a size gives credence to North Korea’s claims of having developed a hydrogen bomb. Estimates from seismic activity led observers to conclude that the explosion likely exceeded two hundred kilotons. The nuclear test carried out on September 3, 2017, was significantly larger, experts say, and indicated that the country has developed much more powerful bomb-making technology. bomb dropped on Hiroshima in 1945, the first atom bomb, had an estimated yield of sixteen kilotons.) The 2009 test had a yield of eight kilotons the 2013 and January 2016 tests both had yields of approximately seventeen kilotons and the September 2016 test had a yield of thirty-five kilotons, according to data from the Nuclear Threat Initiative, a Washington, DC-based nonpartisan think tank. The first explosion in 2006 was a plutonium-fueled atomic bomb with a yield equivalent to two kilotons of TNT, an energy unit used to measure the power of an explosive blast. With each test, North Korea’s nuclear explosions have grown in power. Kim has directed four nuclear tests-in February 2013, January and September 2016, and September 2017-and 160 missile tests, far exceeding the number of trials conducted under his father and grandfather, North Korea’s founder, Kim Il-sung. Under Kim Jong-un, Kim Jong-il’s son who assumed power in late 2011, the nuclear program markedly accelerated. North Korea has conducted six nuclear tests, first in October 2006 and then in May 2009 under former Supreme Leader Kim Jong-il. Kristensen and Matt Korda estimated in 2021 that Pyongyang had enough material for forty to fifty nuclear weapons. Some experts believe the current stockpile of fissile material to be smaller the Bulletin of the Atomic Scientists’ Hans M. Indeed, a 2021 RAND Corporation report projected that North Korea could have around two hundred nuclear weapons stockpiled by 2027. At that rate, in 2022, North Korea could have enough fissile material for more than one hundred nuclear weapons. intelligence officials estimated in 2017 that North Korea had enough fissile material-the core component of nuclear weapons-for up to sixty weapons, and that every year it produces enough fissile material for twelve additional weapons. The North Korean regime possesses the know-how to produce nuclear bombs with weapons-grade uranium or plutonium, the primary elements required for making fissile material.