The part of the United States which is closest to North Korea would be Guam. Some people might say that the closest part of the United States is Hawaii, but it is worthy to note that Guam is an incorporated and organized territory of the United States of America, which technically makes it the closest US territory from North Korea. In fact, Guam is located 2,200 miles southeast of North Korea and around 4,000 miles west of Hawaii.
North Korea even threated to attack Guam in mid-August by releasing an announcement through the country’s official news agency that they will create an “enveloping fire” in Guam “in order to interdict the enemy forces on major military bases on Guam and to signal a crucial warning to the United States.”