 If the North Korean nuclear test is less than even a kiloton in yield, it would be a historically small inaugural nuclear test.Even if it were as many as the reported intentional yield of 4 kt it would be the smallest nuclear test ever conducted by a state as a first test.Some advanced nuclear powers have produced very small tactical nuclear weapons in the low-kiloton range, but their development is far more technologically challenging than that of weapons in the 15–20 kiloton range, requiring advanced weapons materials and core geometries.