The article is here, and mostly quotes PINR’s prior analyses. They see little risk of imminent conflict but rather note that this is a matter of asserting influence in the region:
As PINR stated in May 2005, “it is feasible that Pyongyang would go one step further to declare itself a nuclear power by testing a nuclear device. It may rationalize that its pursuit of nuclear weapons would follow the path pursued by Pakistan and India. In these examples, the international community initially reacted negatively, only to accept grudgingly the nuclear declarations over time. If North Korea were able to develop nuclear weapons without it leading to an attack by the United States, it would dramatically increase its power in East Asia, an outcome that would drastically alter the balance of power in the region.”
In addition, they suggest that this may spark an arms race between Japan and China, since Tokyo may not wish to be the only major player in the area without nukes of its own, and this will provoke more weapons spending in China:
“A nuclear weapon capable Japan will certainly push China to continue its military modernization program since Beijing sees Tokyo as a potential threat to its long-term interests in the Asia Pacific region. “
That said, I can’t tell whether Americans are experiencing this test as a major threat. Certainly the administration has kept its rhetoric soft, so perhaps this whole affair will simply blow over… you know, like a mushroom cloud on a sunny day.