North Korea dramatically escalated tensions by testing a very powerful bomb today. Experts are skeptical that it was a hydrogen bomb. However, it is at least 10x more powerful than anything North Korea had up to this point.
The test was actually directed at China more than the US. In short, it was designed to put pressure on the Chinese to bring the Americans to the bargaining table. Instead it has infuriated the Chines and more than likely increased the probability of stronger action by the US.
What makes this dangerous is that the accuracy of the ICBMs don’t have to be high in order to cause severe damage to a city. Add in the recent advances in the distance of the ICBMs that North Korea now has and it is easy to see that the risk level has increased significantly.