The answer may be as simple as 'it was too risky.'
North Korean leader Kim Jong-un has recently been photographed with an unknown woman, causing international buzz.
Once completed, the North Korean reactor would be able to produce enough plutonium for a new bomb every year, according to the US-Korea Institute at Johns Hopkins University.
North Korea threat: Washington says it has traced the sale of truck parts North Korea used to transport missiles to a Chinese company. Is Beijing not fully enforcing sanctions on North Korea?
Citing the United States' postponement of delivery of food aid, North Korea says that it is no longer obligated to hold off on nuclear development.
After weeks of preparation, as well as warnings and condemnation from the international community, North Korea is ready to launch a long-range rocket.
The threat of such a test, coming amid plans to test a controversial rocket this week, is seen as an effort by North Korea to extort more aid from the international community.