The war of words between the United States and North Korea is escalating, and the world is watching intently to see what each country does next. In the most recent addition to their heated back-and-forth, North Korean leader Kim Jong Un threatened to carry out an atmospheric nuclear test over the Pacific Ocean. But even this display would simply be the latest in a lengthy series of missile and nuclear tests that spans over a decade. Each new step that Pyongyang has taken in its development of missile and nuclear technology has been critical to its goal of acquiring a viable nuclear deterrent to U.S. military action against it. And further strides are on the horizon....