Just as the United States allowed Pakistan to proliferate nuclear bomb technology to its islamic brothers, it may look the other way if we pass on the bomb tech to our friendly nations such as South Korea and Japan. It may encourage us to do so as tacitly as it did with Pak. USA may look the other way because that would be one other method of controlling China. After all what has it done in the case of Pakistan after its weapons proliferation? It has only rewarded it with nearly 25 billion US dollars, F16 aircrafts and the like. So, you never know.