North Korea's possible nuke test forecast

North Korea has continued high-explosive detonation tests and its possible nuclear test is forecast to be much more powerful both in scale and yield than previous ones, Seoul's Yonhap News Agency reported Wednesday, citing intelligence authorities.
"North Korea has been carrying out high-explosive tests at a test site in Pyongyang to secure technology for weapons miniaturization and stronger explosive power," an official was quoted as saying. "Should the North conduct a fourth round of nuclear test, its explosion would have a yield of at least 10 to 15 kilotons with a larger scale compared to the previous ones," he added.
The North's initial underground test in 2006 was measured at 3.9 on the Richter scale with a wield of less than 1 kiloton. In May 2009, Pyongyang carried out the second test that created a 4.5-magnitude tremor with a yield of 3 to 4 kilotons. During the third and the latest test in February 2013, the figures jumped to 4.9 on scale and 6-7 kilotons, according to South Korean and the US authorities. "No unusual signs have been detected in and around its nuclear test site. But Pyongyang has been ready to carry out a fresh test round whenever it wants," the official noted.
The North has repeatedly vowed to develop its economy and nuclear arsenal in tandem under the notion that the destructive weapons programs are a deterrent against what it claims is the US' hostile policy against it. The regime was also estimated to have increased its nuclear stockpile.
"North Korea has revved up efforts to secure more weapons-grade plutonium and to have the highly enriched uranium program, though the exact amounts are not known," another Seoul official said.
In its 2014 white paper, Seoul said the North is presumed to have secured some 40 kilograms of weapons-grade plutonium, "but the figure is literally nothing but a presumption," he said.