In an unprecedented announcement on Thursday, North Korea's state media said the country is developing a plan to simultaneously test-fire four intermediate ballistic missiles into the sea near Guam by mid-August, with a flight plan that would see them fly over Shimane, Hiroshima and Kochi prefectures.

The Hwasong-12 rockets will fly 3,356.7 km for 1,065 seconds and hit the waters 30 to 40 km away from Guam "to signal a crucial warning to the U.S.," the Korean Central News Agency said.

Guam hosts key U.S. military bases, including Andersen Air Force Base, where B-1B heavy bombers have been deployed to fly over the Korean Peninsula in a demonstration of military power to Pyongyang.