North Korea has carried out up to 70 tests as part of its nuclear weapons programme, according to South Korean sources.
The communist regime is alleged to have reprocessed a small number of its spent nuclear fuel rods, which could provide it with weapons-grade plutonium.
Intelligence director Ko Young-koo told parliament that his staff had noticed tests on high-explosive - which can be used to detonate nuclear devices -being conducted near the nuclear site in Yongbyon.
How much longer . . . . . . . .
(Can also be read here. And here. And here. And here. )