You might want to consult a good atlas. The distance from Diego Garcia (in the central Indian Ocean) to North Korea (in the northwest Pacific) is over 4,500 miles, so better staging and basing locations are available. By comparison, Hawaii and Guam are closer, and Japan is practically next door at 500 miles.
They don't want a fight with us. The first move they make at the DMZ and that's their a$$. It'll take about 20 minutes for the bombers to arrive from the Indian Ocean.
Glad to know that it's all so easy. And that our bombers can fly so far so fast. But just in case, we won't throw out the old OPLAN just yet...