North Korea is conducting nuclear tests under a volcano. Their previous tests have been largely unsuccessful, and it turns out that might have been a good thing. They bury their underground nuclear tests at Mount Mantap, near the huge volcano Mount Baekdu*, which has been mostly dormant for a thousand years. Well, it used to be dormant, before they started using nukes to wake it up.
On Oct. 1, 2006, a Russian satellite found the surface temperature of the mountain notably higher than before. The finding came just days after North Korea conducted an underground nuclear test in its northern territory, which could have been a catalyst reactivating magma flows, according to analysts. (Global Disaster Watch)
Yes, North Korean nuclear tests may trigger the first human-caused volcanic eruption. This claim is so crazy that it bears repeating, but that's not what makes it a nuclear volcano. The radiation would be generated Japanese-tsunami-style. There are at least 6 Chinese and an unknown amount of North Korean nuclear power plants in the area. When Baekdu pops, the power plants may be breached, and then all of Southeast Asia will get to share in the fun.
China plans to build nuclear plants near Mount Baekdu bordering North Korea, with nuclear reactors under construction on the edge of the Liaoning Peninsula of Liaoning Province to go online next year as scheduled. In case of accident, the fallout from the plants will directly affect the Korean Peninsula. (BusiUnion)
Other fun facts. Kim Jong Il received his Juche Commandments from a talking moon-lotus on Mt. Baekdu. Koreans (North and South) love the hot springs there. Oh, and Baekdu has been responsible for destroying Korea (Balhae) before. The last time this volcano had a major eruption in 946 AD, it crippled the existing Korean empire and made them vulnerable to foreign invaders. If Baekdu erupted again, it would affect the entire area, including Japan, South Korea, and parts of China and Russia, all covered in a heavy blanket of ash, possibly followed up by a radioactive disaster.
We can't know for sure if nuclear explosions can wake up a dormant volcano until it happens. It was only recently that the first proven man-made earthquakes were recorded, a consequence of ground water tampering caused by 'fracking' oil extraction. It has only been a couple decades since humanity detected and resolved our assault on the ozone layer with chlorofluorocarbons. People still debate human-caused global warming. We are just now coming to terms with the immense power the human race has to alter our environment. Until the day we (accidentally?) bury a (functional) nuke under a big volcanic range and then watch it erupt, we won't know our own strength. At that time, it will be too late. Let's hope North Korea's shitty nuclear technology will fail again.
Long article with lots of detail:
Extensive post from Kushibo. Read this!
*Baekdu is known by the Chinese as Changbai Mountain and Baitou Mountain. The caldera (pictured above) is Heaven Lake.