It isn't part of a good energy strategy. It has cost too much and hurt their economy too much. If it is for the purpose of nuclear weapons, it doesn't make much sense because all of the likely targets are upwind. A nuclear weapon is nothing more than a national suicide bomb. The best answer is that its just a matter of national pride. Other nations have done similar things. It was similar national pride that drove the U.S. to land men on the moon.