When a magnitude 4.9 earthquake was detected in North Korea on Tuesday in an area that isn’t prone to seismic activity, it didn’t take long to figure out what had happened. The tremor, which experts in South Korea called an “artificial earthquake,” was soon confirmed to be the underground nuclear test that the country has been threatening for some time. “A third nuclear test has been successfully staged,” North Korea’s state news agency confirmed several hours later, adding that the test was conducted “to defend the country’s security and sovereignty in the face of the ferocious hostile act of the U.S.”
North Korea says the explosive was a “a smaller and light A-bomb unlike the previous ones,” and the New York Times reports that preliminary estimates suggest the test was much larger than the last two, but less powerful than the bomb dropped on Hiroshima. While North Korea is always quick to declare a victory, it could take days or weeks to determine if the test was successful, and whether a plutonium or uranium weapon was used. Previously, North Korea has used its limited supply of plutonium from defunct nuclear reactors, but as the Washington Post explains, if the country develops the ability to enrich uranium, it could produce many more bombs that are more difficult to detect.