North Korea has tested missiles in a clear attempt to intimidate its neighbors. This is an act of war, and it is an affront to the sovereignty of South Korea. Since there is an extremely sensitive political situation that involved a host of international partners, any launch would be a mistake. It is extremely irresponsible for North Korea's leaders to behave in this way, especially when many of its people rely on foreign aid for basic human sustenance.
Yes, North Korea is overstepping it's bounds with the missile launch. It's an obvious violation of U.N. sanctions, and complete disregard for international opposition. In addition, North Korea moved up the launch for real reason, and it seems to me that they are actually hiding the fact that they are preparing for nuclear war.
North Korea has gone too far with the latest missile launch because they are in no position to launch missiles. Most countries around the world have put pressure on them to stop, including their ally China, so they have no room to be launching missiles because they have nothing to gain since the international community is against it.
I believe that North Korea has every right to study missile launches at their own discretion. The need to launch a missile may become necessary in the future, making it important to practice. They did not pose a threat to the United States or any other country and they are not hiding the fact that they have been researching the effect of missiles. Although two objects have been spotted in the atmosphere, there is no concrete evidence that they will ever cause any harm in the future.